diff --git a/ra_aid/__main__.py b/ra_aid/__main__.py
index 3121e5d..d613041 100644
--- a/ra_aid/__main__.py
+++ b/ra_aid/__main__.py
@@ -39,35 +39,41 @@ from ra_aid.agents.research_agent import run_research_agent
 from ra_aid.agents import run_planning_agent
 from ra_aid.config import (
     DEFAULT_MAX_TEST_CMD_RETRIES,
+    DEFAULT_MODEL,
     DEFAULT_RECURSION_LIMIT,
     DEFAULT_TEST_CMD_TIMEOUT,
     VALID_PROVIDERS,
 )
-from ra_aid.database.repositories.key_fact_repository import KeyFactRepositoryManager, get_key_fact_repository
+from ra_aid.database.repositories.key_fact_repository import (
+    KeyFactRepositoryManager,
+    get_key_fact_repository,
+)
 from ra_aid.database.repositories.key_snippet_repository import (
-    KeySnippetRepositoryManager, get_key_snippet_repository
+    KeySnippetRepositoryManager,
+    get_key_snippet_repository,
 )
 from ra_aid.database.repositories.human_input_repository import (
-    HumanInputRepositoryManager, get_human_input_repository
+    HumanInputRepositoryManager,
+    get_human_input_repository,
 )
 from ra_aid.database.repositories.research_note_repository import (
-    ResearchNoteRepositoryManager, get_research_note_repository
+    ResearchNoteRepositoryManager,
+    get_research_note_repository,
 )
 from ra_aid.database.repositories.trajectory_repository import (
-    TrajectoryRepositoryManager, get_trajectory_repository
+    TrajectoryRepositoryManager,
+    get_trajectory_repository,
 )
 from ra_aid.database.repositories.session_repository import (
     SessionRepositoryManager, get_session_repository
 )
 from ra_aid.database.repositories.related_files_repository import (
-    RelatedFilesRepositoryManager
-)
-from ra_aid.database.repositories.work_log_repository import (
-    WorkLogRepositoryManager
+    RelatedFilesRepositoryManager,
 )
+from ra_aid.database.repositories.work_log_repository import WorkLogRepositoryManager
 from ra_aid.database.repositories.config_repository import (
     ConfigRepositoryManager,
-    get_config_repository
+    get_config_repository,
 )
 from ra_aid.env_inv import EnvDiscovery
 from ra_aid.env_inv_context import EnvInvManager, get_env_inv
@@ -103,9 +109,9 @@ def launch_webui(host: str, port: int):
 
 
 def parse_arguments(args=None):
-    ANTHROPIC_DEFAULT_MODEL = "claude-3-7-sonnet-20250219"
+    ANTHROPIC_DEFAULT_MODEL = DEFAULT_MODEL
     OPENAI_DEFAULT_MODEL = "gpt-4o"
-    
+
     # Case-insensitive log level argument type
     def log_level_type(value):
         value = value.lower()
@@ -202,8 +208,10 @@ Examples:
         help="Enable chat mode with direct human interaction (implies --hil)",
     )
     parser.add_argument(
-        "--log-mode", choices=["console", "file"], default="file", 
-        help="Logging mode: 'console' shows all logs in console, 'file' logs to file with only warnings+ in console"
+        "--log-mode",
+        choices=["console", "file"],
+        default="file",
+        help="Logging mode: 'console' shows all logs in console, 'file' logs to file with only warnings+ in console",
     )
     parser.add_argument(
         "--pretty-logger", action="store_true", help="Enable pretty logging output"
@@ -386,20 +394,20 @@ def is_stage_requested(stage: str) -> bool:
 
 def wipe_project_memory():
     """Delete the project database file to wipe all stored memory.
-    
+
     Returns:
         str: A message indicating the result of the operation
     """
     import os
     from pathlib import Path
-    
+
     cwd = os.getcwd()
     ra_aid_dir = Path(os.path.join(cwd, ".ra-aid"))
     db_path = os.path.join(ra_aid_dir, "pk.db")
-    
+
     if not os.path.exists(db_path):
         return "No project memory found to wipe."
-    
+
     try:
         os.remove(db_path)
         return "Project memory wiped successfully."
@@ -411,11 +419,11 @@ def wipe_project_memory():
 
 def build_status():
     """Build status panel with model and feature information.
-    
+
     Includes memory statistics at the bottom with counts of key facts, snippets, and research notes.
     """
     status = Text()
-    
+
     # Get the config repository to get model/provider information
     config_repo = get_config_repository()
     provider = config_repo.get("provider", "")
@@ -423,12 +431,14 @@ def build_status():
     temperature = config_repo.get("temperature")
     expert_provider = config_repo.get("expert_provider", "")
     expert_model = config_repo.get("expert_model", "")
-    experimental_fallback_handler = config_repo.get("experimental_fallback_handler", False)
+    experimental_fallback_handler = config_repo.get(
+        "experimental_fallback_handler", False
+    )
     web_research_enabled = config_repo.get("web_research_enabled", False)
-    
+
     # Get the expert enabled status
     expert_enabled = bool(expert_provider and expert_model)
-    
+
     # Basic model information
     status.append("🤖 ")
     status.append(f"{provider}/{model}")
@@ -460,39 +470,41 @@ def build_status():
             [fb_handler._format_model(m) for m in fb_handler.fallback_tool_models]
         )
         status.append(msg)
-    
+
     # Add memory statistics
     # Get counts of key facts, snippets, and research notes with error handling
     fact_count = 0
     snippet_count = 0
     note_count = 0
-    
+
     try:
         fact_count = len(get_key_fact_repository().get_all())
     except RuntimeError as e:
         logger.debug(f"Failed to get key facts count: {e}")
-    
+
     try:
         snippet_count = len(get_key_snippet_repository().get_all())
     except RuntimeError as e:
         logger.debug(f"Failed to get key snippets count: {e}")
-    
+
     try:
         note_count = len(get_research_note_repository().get_all())
     except RuntimeError as e:
         logger.debug(f"Failed to get research notes count: {e}")
-    
+
     # Add memory statistics line with reset option note
-    status.append(f"\n💾 Memory: {fact_count} facts, {snippet_count} snippets, {note_count} notes")
+    status.append(
+        f"\n💾 Memory: {fact_count} facts, {snippet_count} snippets, {note_count} notes"
+    )
     if fact_count > 0 or snippet_count > 0 or note_count > 0:
         status.append(" (use --wipe-project-memory to reset)")
-    
+
     # Check for newer version
     version_message = check_for_newer_version()
     if version_message:
         status.append("\n\n")
         status.append(version_message, style="yellow")
-    
+
     return status
 
 
@@ -501,7 +513,7 @@ def main():
     args = parse_arguments()
     setup_logging(args.log_mode, args.pretty_logger, args.log_level)
     logger.debug("Starting RA.Aid with arguments: %s", args)
-    
+
     # Check if we need to wipe project memory before starting
     if args.wipe_project_memory:
         result = wipe_project_memory()
@@ -527,7 +539,7 @@ def main():
 
             # Initialize empty config dictionary to be populated later
             config = {}
-            
+
             # Initialize repositories with database connection
             # Create environment inventory data
             env_discovery = EnvDiscovery()
@@ -568,7 +580,9 @@ def main():
                     expert_missing,
                     web_research_enabled,
                     web_research_missing,
-                ) = validate_environment(args)  # Will exit if main env vars missing
+                ) = validate_environment(
+                    args
+                )  # Will exit if main env vars missing
                 logger.debug("Environment validation successful")
 
                 # Validate model configuration early
@@ -604,12 +618,16 @@ def main():
                 config_repo.set("expert_provider", args.expert_provider)
                 config_repo.set("expert_model", args.expert_model)
                 config_repo.set("temperature", args.temperature)
-                config_repo.set("experimental_fallback_handler", args.experimental_fallback_handler)
+                config_repo.set(
+                    "experimental_fallback_handler", args.experimental_fallback_handler
+                )
                 config_repo.set("web_research_enabled", web_research_enabled)
                 config_repo.set("show_thoughts", args.show_thoughts)
                 config_repo.set("show_cost", args.show_cost)
                 config_repo.set("force_reasoning_assistance", args.reasoning_assistance)
-                config_repo.set("disable_reasoning_assistance", args.no_reasoning_assistance)
+                config_repo.set(
+                    "disable_reasoning_assistance", args.no_reasoning_assistance
+                )
 
                 # Build status panel with memory statistics
                 status = build_status()
@@ -678,13 +696,15 @@ def main():
                     initial_request = ask_human.invoke(
                         {"question": "What would you like help with?"}
                     )
-                    
+
                     # Record chat input in database (redundant as ask_human already records it,
                     # but needed in case the ask_human implementation changes)
                     try:
                         # Using get_human_input_repository() to access the repository from context
                         human_input_repository = get_human_input_repository()
-                        human_input_repository.create(content=initial_request, source='chat')
+                        human_input_repository.create(
+                            content=initial_request, source="chat"
+                        )
                         human_input_repository.garbage_collect()
                     except Exception as e:
                         logger.error(f"Failed to record initial chat input: {str(e)}")
@@ -742,8 +762,12 @@ def main():
                             ),
                             working_directory=working_directory,
                             current_date=current_date,
-                            key_facts=format_key_facts_dict(get_key_fact_repository().get_facts_dict()),
-                            key_snippets=format_key_snippets_dict(get_key_snippet_repository().get_snippets_dict()),
+                            key_facts=format_key_facts_dict(
+                                get_key_fact_repository().get_facts_dict()
+                            ),
+                            key_snippets=format_key_snippets_dict(
+                                get_key_snippet_repository().get_snippets_dict()
+                            ),
                             project_info=formatted_project_info,
                             env_inv=get_env_inv(),
                         ),
@@ -775,12 +799,12 @@ def main():
                     sys.exit(1)
 
                 base_task = args.message
-                
+
                 # Record CLI input in database
                 try:
                     # Using get_human_input_repository() to access the repository from context
                     human_input_repository = get_human_input_repository()
-                    human_input_repository.create(content=base_task, source='cli')
+                    human_input_repository.create(content=base_task, source="cli")
                     # Run garbage collection to ensure we don't exceed 100 inputs
                     human_input_repository.garbage_collect()
                     logger.debug(f"Recorded CLI input: {base_task}")
@@ -814,19 +838,25 @@ def main():
                 config_repo.set("expert_model", args.expert_model)
 
                 # Store planner config with fallback to base values
-                config_repo.set("planner_provider", args.planner_provider or args.provider)
+                config_repo.set(
+                    "planner_provider", args.planner_provider or args.provider
+                )
                 config_repo.set("planner_model", args.planner_model or args.model)
 
                 # Store research config with fallback to base values
-                config_repo.set("research_provider", args.research_provider or args.provider)
+                config_repo.set(
+                    "research_provider", args.research_provider or args.provider
+                )
                 config_repo.set("research_model", args.research_model or args.model)
 
                 # Store temperature in config
                 config_repo.set("temperature", args.temperature)
-                
+
                 # Store reasoning assistance flags
                 config_repo.set("force_reasoning_assistance", args.reasoning_assistance)
-                config_repo.set("disable_reasoning_assistance", args.no_reasoning_assistance)
+                config_repo.set(
+                    "disable_reasoning_assistance", args.no_reasoning_assistance
+                )
 
                 # Set modification tools based on use_aider flag
                 set_modification_tools(args.use_aider)
@@ -870,5 +900,6 @@ def main():
         print()
         sys.exit(0)
 
+
 if __name__ == "__main__":
     main()
diff --git a/ra_aid/agent_utils.py b/ra_aid/agent_utils.py
index bef5bd5..fa1ff62 100644
--- a/ra_aid/agent_utils.py
+++ b/ra_aid/agent_utils.py
@@ -1,19 +1,14 @@
 """Utility functions for working with agents."""
 
-import inspect
-import os
 import signal
 import sys
 import threading
 import time
-import uuid
-from datetime import datetime
-from typing import Any, Dict, List, Literal, Optional, Sequence
+from typing import Any, Dict, List, Literal, Optional
 
+from langchain_anthropic import ChatAnthropic
 from ra_aid.callbacks.anthropic_callback_handler import AnthropicCallbackHandler
 
-
-import litellm
 from anthropic import APIError, APITimeoutError, InternalServerError, RateLimitError
 from openai import RateLimitError as OpenAIRateLimitError
 from litellm.exceptions import RateLimitError as LiteLLMRateLimitError
@@ -23,28 +18,24 @@ from langchain_core.messages import (
     BaseMessage,
     HumanMessage,
     SystemMessage,
-    trim_messages,
 )
 from langchain_core.tools import tool
-from langgraph.checkpoint.memory import MemorySaver
 from langgraph.prebuilt import create_react_agent
 from langgraph.prebuilt.chat_agent_executor import AgentState
-from litellm import get_model_info
 from rich.console import Console
 from rich.markdown import Markdown
 from rich.panel import Panel
 
 from ra_aid.agent_context import (
     agent_context,
-    get_depth,
     is_completed,
     reset_completion_flags,
     should_exit,
 )
 from ra_aid.agent_backends.ciayn_agent import CiaynAgent
 from ra_aid.agents_alias import RAgents
-from ra_aid.config import DEFAULT_MAX_TEST_CMD_RETRIES, DEFAULT_RECURSION_LIMIT
-from ra_aid.console.formatting import print_error, print_stage_header
+from ra_aid.config import DEFAULT_MAX_TEST_CMD_RETRIES
+from ra_aid.console.formatting import print_error
 from ra_aid.console.output import print_agent_output
 from ra_aid.exceptions import (
     AgentInterrupt,
@@ -53,77 +44,20 @@ from ra_aid.exceptions import (
 )
 from ra_aid.fallback_handler import FallbackHandler
 from ra_aid.logging_config import get_logger
-from ra_aid.llm import initialize_expert_llm
-from ra_aid.models_params import DEFAULT_TOKEN_LIMIT, models_params
-from ra_aid.text.processing import process_thinking_content
-from ra_aid.project_info import (
-    display_project_status,
-    format_project_info,
-    get_project_info,
-)
-from ra_aid.prompts.expert_prompts import (
-    EXPERT_PROMPT_SECTION_IMPLEMENTATION,
-    EXPERT_PROMPT_SECTION_PLANNING,
-    EXPERT_PROMPT_SECTION_RESEARCH,
-)
-from ra_aid.prompts.human_prompts import (
-    HUMAN_PROMPT_SECTION_IMPLEMENTATION,
-    HUMAN_PROMPT_SECTION_PLANNING,
-    HUMAN_PROMPT_SECTION_RESEARCH,
-)
-from ra_aid.prompts.implementation_prompts import IMPLEMENTATION_PROMPT
-from ra_aid.prompts.common_prompts import NEW_PROJECT_HINTS
-from ra_aid.prompts.planning_prompts import PLANNING_PROMPT
-from ra_aid.prompts.reasoning_assist_prompt import (
-    REASONING_ASSIST_PROMPT_PLANNING,
-    REASONING_ASSIST_PROMPT_IMPLEMENTATION,
-    REASONING_ASSIST_PROMPT_RESEARCH,
-)
-from ra_aid.prompts.research_prompts import (
-    RESEARCH_ONLY_PROMPT,
-    RESEARCH_PROMPT,
-)
-from ra_aid.prompts.web_research_prompts import (
-    WEB_RESEARCH_PROMPT,
-    WEB_RESEARCH_PROMPT_SECTION_CHAT,
-    WEB_RESEARCH_PROMPT_SECTION_PLANNING,
-    WEB_RESEARCH_PROMPT_SECTION_RESEARCH,
-)
-from ra_aid.tool_configs import (
-    get_implementation_tools,
-    get_planning_tools,
-    get_research_tools,
-    get_web_research_tools,
-)
+from ra_aid.models_params import DEFAULT_TOKEN_LIMIT
 from ra_aid.tools.handle_user_defined_test_cmd_execution import execute_test_command
-from ra_aid.database.repositories.key_fact_repository import get_key_fact_repository
-from ra_aid.database.repositories.key_snippet_repository import (
-    get_key_snippet_repository,
-)
 from ra_aid.database.repositories.human_input_repository import (
     get_human_input_repository,
 )
-from ra_aid.database.repositories.research_note_repository import (
-    get_research_note_repository,
-)
 from ra_aid.database.repositories.trajectory_repository import get_trajectory_repository
-from ra_aid.database.repositories.work_log_repository import get_work_log_repository
-from ra_aid.model_formatters import format_key_facts_dict
-from ra_aid.model_formatters.key_snippets_formatter import format_key_snippets_dict
-from ra_aid.model_formatters.research_notes_formatter import format_research_notes_dict
-from ra_aid.tools.memory import (
-    get_related_files,
-    log_work_event,
-)
 from ra_aid.database.repositories.config_repository import get_config_repository
-from ra_aid.env_inv_context import get_env_inv
+from ra_aid.anthropic_token_limiter import sonnet_35_state_modifier, state_modifier, get_model_token_limit
 
 console = Console()
 
 logger = get_logger(__name__)
 
 # Import repositories using get_* functions
-from ra_aid.database.repositories.key_fact_repository import get_key_fact_repository
 
 
 @tool
@@ -133,131 +67,19 @@ def output_markdown_message(message: str) -> str:
     return "Message output."
 
 
-def estimate_messages_tokens(messages: Sequence[BaseMessage]) -> int:
-    """Helper function to estimate total tokens in a sequence of messages.
-
-    Args:
-        messages: Sequence of messages to count tokens for
-
-    Returns:
-        Total estimated token count
-    """
-    if not messages:
-        return 0
-
-    estimate_tokens = CiaynAgent._estimate_tokens
-    return sum(estimate_tokens(msg) for msg in messages)
-
-
-def state_modifier(
-    state: AgentState, max_input_tokens: int = DEFAULT_TOKEN_LIMIT
-) -> list[BaseMessage]:
-    """Given the agent state and max_tokens, return a trimmed list of messages.
-
-    Args:
-        state: The current agent state containing messages
-        max_tokens: Maximum number of tokens to allow (default: DEFAULT_TOKEN_LIMIT)
-
-    Returns:
-        list[BaseMessage]: Trimmed list of messages that fits within token limit
-    """
-    messages = state["messages"]
-
-    if not messages:
-        return []
-
-    first_message = messages[0]
-    remaining_messages = messages[1:]
-    first_tokens = estimate_messages_tokens([first_message])
-    new_max_tokens = max_input_tokens - first_tokens
-
-    trimmed_remaining = trim_messages(
-        remaining_messages,
-        token_counter=estimate_messages_tokens,
-        max_tokens=new_max_tokens,
-        strategy="last",
-        allow_partial=False,
-    )
-
-    return [first_message] + trimmed_remaining
-
-
-def get_model_token_limit(
-    config: Dict[str, Any], agent_type: Literal["default", "research", "planner"]
-) -> Optional[int]:
-    """Get the token limit for the current model configuration based on agent type.
-
-    Returns:
-        Optional[int]: The token limit if found, None otherwise
-    """
-    try:
-        # Try to get config from repository for production use
-        try:
-            config_from_repo = get_config_repository().get_all()
-            # If we succeeded, use the repository config instead of passed config
-            config = config_from_repo
-        except RuntimeError:
-            # In tests, this may fail because the repository isn't set up
-            # So we'll use the passed config directly
-            pass
-        if agent_type == "research":
-            provider = config.get("research_provider", "") or config.get("provider", "")
-            model_name = config.get("research_model", "") or config.get("model", "")
-        elif agent_type == "planner":
-            provider = config.get("planner_provider", "") or config.get("provider", "")
-            model_name = config.get("planner_model", "") or config.get("model", "")
-        else:
-            provider = config.get("provider", "")
-            model_name = config.get("model", "")
-
-        try:
-            provider_model = model_name if not provider else f"{provider}/{model_name}"
-            model_info = get_model_info(provider_model)
-            max_input_tokens = model_info.get("max_input_tokens")
-            if max_input_tokens:
-                logger.debug(
-                    f"Using litellm token limit for {model_name}: {max_input_tokens}"
-                )
-                return max_input_tokens
-        except litellm.exceptions.NotFoundError:
-            logger.debug(
-                f"Model {model_name} not found in litellm, falling back to models_params"
-            )
-        except Exception as e:
-            logger.debug(
-                f"Error getting model info from litellm: {e}, falling back to models_params"
-            )
-
-        # Fallback to models_params dict
-        # Normalize model name for fallback lookup (e.g. claude-2 -> claude2)
-        normalized_name = model_name.replace("-", "")
-        provider_tokens = models_params.get(provider, {})
-        if normalized_name in provider_tokens:
-            max_input_tokens = provider_tokens[normalized_name]["token_limit"]
-            logger.debug(
-                f"Found token limit for {provider}/{model_name}: {max_input_tokens}"
-            )
-        else:
-            max_input_tokens = None
-            logger.debug(f"Could not find token limit for {provider}/{model_name}")
-
-        return max_input_tokens
-
-    except Exception as e:
-        logger.warning(f"Failed to get model token limit: {e}")
-        return None
 
 
 def build_agent_kwargs(
     checkpointer: Optional[Any] = None,
+    model: ChatAnthropic = None,
     max_input_tokens: Optional[int] = None,
 ) -> Dict[str, Any]:
     """Build kwargs dictionary for agent creation.
 
     Args:
         checkpointer: Optional memory checkpointer
-        config: Optional configuration dictionary
-        token_limit: Optional token limit for the model
+        model: The language model to use for token counting
+        max_input_tokens: Optional token limit for the model
 
     Returns:
         Dictionary of kwargs for agent creation
@@ -270,12 +92,20 @@ def build_agent_kwargs(
         agent_kwargs["checkpointer"] = checkpointer
 
     config = get_config_repository().get_all()
-    if config.get("limit_tokens", True) and is_anthropic_claude(config):
+    if (
+        config.get("limit_tokens", True)
+        and is_anthropic_claude(config)
+        and model is not None
+    ):
 
         def wrapped_state_modifier(state: AgentState) -> list[BaseMessage]:
-            return state_modifier(state, max_input_tokens=max_input_tokens)
+            if any(pattern in model.model for pattern in ["claude-3.5", "claude3.5", "claude-3-5"]):
+                return sonnet_35_state_modifier(state, max_input_tokens=max_input_tokens)
+
+            return state_modifier(state, model, max_input_tokens=max_input_tokens)
 
         agent_kwargs["state_modifier"] = wrapped_state_modifier
+    agent_kwargs["name"] = "React"
 
     return agent_kwargs
 
@@ -345,7 +175,8 @@ def create_agent(
         # Use REACT agent for Anthropic Claude models, otherwise use CIAYN
         if is_anthropic_claude(config):
             logger.debug("Using create_react_agent to instantiate agent.")
-            agent_kwargs = build_agent_kwargs(checkpointer, max_input_tokens)
+
+            agent_kwargs = build_agent_kwargs(checkpointer, model, max_input_tokens)
             return create_react_agent(
                 model, tools, interrupt_after=["tools"], **agent_kwargs
             )
@@ -358,16 +189,12 @@ def create_agent(
         logger.warning(f"Failed to detect model type: {e}. Defaulting to REACT agent.")
         config = get_config_repository().get_all()
         max_input_tokens = get_model_token_limit(config, agent_type)
-        agent_kwargs = build_agent_kwargs(checkpointer, max_input_tokens)
+        agent_kwargs = build_agent_kwargs(checkpointer, model, max_input_tokens)
         return create_react_agent(
             model, tools, interrupt_after=["tools"], **agent_kwargs
         )
 
 
-from ra_aid.agents.research_agent import run_research_agent, run_web_research_agent
-from ra_aid.agents.implementation_agent import run_task_implementation_agent
-
-
 _CONTEXT_STACK = []
 _INTERRUPT_CONTEXT = None
 _FEEDBACK_MODE = False
diff --git a/ra_aid/anthropic_message_utils.py b/ra_aid/anthropic_message_utils.py
new file mode 100644
index 0000000..79f271e
--- /dev/null
+++ b/ra_aid/anthropic_message_utils.py
@@ -0,0 +1,312 @@
+"""Utilities for handling Anthropic-specific message formats and trimming."""
+
+from typing import Callable, List, Literal, Optional, Sequence, Union, cast
+
+from langchain_core.messages import (
+    AIMessage,
+    BaseMessage,
+    ChatMessage,
+    FunctionMessage,
+    HumanMessage,
+    SystemMessage,
+    ToolMessage,
+)
+
+
+def _is_message_type(
+    message: BaseMessage, message_types: Union[str, type, List[Union[str, type]]]
+) -> bool:
+    """Check if a message is of a specific type or types.
+
+    Args:
+        message: The message to check
+        message_types: Type(s) to check against (string name or class)
+
+    Returns:
+        bool: True if message matches any of the specified types
+    """
+    if not isinstance(message_types, list):
+        message_types = [message_types]
+
+    types_str = [t for t in message_types if isinstance(t, str)]
+    types_classes = tuple(t for t in message_types if isinstance(t, type))
+
+    return message.type in types_str or isinstance(message, types_classes)
+
+
+def has_tool_use(message: BaseMessage) -> bool:
+    """Check if a message contains tool use.
+
+    Args:
+        message: The message to check
+
+    Returns:
+        bool: True if the message contains tool use
+    """
+    if not isinstance(message, AIMessage):
+        return False
+
+    # Check content for tool_use
+    if isinstance(message.content, str) and "tool_use" in message.content:
+        return True
+
+    # Check content list for tool_use blocks
+    if isinstance(message.content, list):
+        for item in message.content:
+            if isinstance(item, dict) and item.get("type") == "tool_use":
+                return True
+
+    # Check additional_kwargs for tool_calls
+    if hasattr(message, "additional_kwargs") and message.additional_kwargs.get(
+        "tool_calls"
+    ):
+        return True
+
+    return False
+
+
+def is_tool_pair(message1: BaseMessage, message2: BaseMessage) -> bool:
+    """Check if two messages form a tool use/result pair.
+
+    Args:
+        message1: First message
+        message2: Second message
+
+    Returns:
+        bool: True if the messages form a tool use/result pair
+    """
+    return (
+        isinstance(message1, AIMessage)
+        and isinstance(message2, ToolMessage)
+        and has_tool_use(message1)
+    )
+
+
+
+def anthropic_trim_messages(
+    messages: Sequence[BaseMessage],
+    *,
+    max_tokens: int,
+    token_counter: Callable[[List[BaseMessage]], int],
+    strategy: Literal["first", "last"] = "last",
+    num_messages_to_keep: int = 2,
+    allow_partial: bool = False,
+    include_system: bool = True,
+    start_on: Optional[Union[str, type, List[Union[str, type]]]] = None,
+) -> List[BaseMessage]:
+    """Trim messages to fit within a token limit, with Anthropic-specific handling.
+
+    Warning - not fully implemented - last strategy is supported and test, not
+    allow partial, not 'first' strategy either.
+    This function is similar to langchain_core's trim_messages but with special
+    handling for Anthropic message formats to avoid API errors.
+
+    It always keeps the first num_messages_to_keep messages.
+
+    Args:
+        messages: Sequence of messages to trim
+        max_tokens: Maximum number of tokens allowed
+        token_counter: Function to count tokens in messages
+        strategy: Whether to keep the "first" or "last" messages
+        allow_partial: Whether to allow partial messages
+        include_system: Whether to always include the system message
+        start_on: Message type to start on (only for "last" strategy)
+
+    Returns:
+        List[BaseMessage]: Trimmed messages that fit within token limit
+    """
+    if not messages:
+        return []
+
+    messages = list(messages)
+
+    # Always keep the first num_messages_to_keep messages
+    kept_messages = messages[:num_messages_to_keep]
+    remaining_msgs = messages[num_messages_to_keep:]
+
+
+    # For Anthropic, we need to maintain the conversation structure where:
+    # 1. Every AIMessage with tool_use must be followed by a ToolMessage
+    # 2. Every AIMessage that follows a ToolMessage must start with a tool_result
+
+    # First, check if we have any tool_use in the messages
+    has_tool_use_anywhere = any(has_tool_use(msg) for msg in messages)
+
+    # If we have tool_use anywhere, we need to be very careful about trimming
+    if has_tool_use_anywhere:
+        # For safety, just keep all messages if we're under the token limit
+        if token_counter(messages) <= max_tokens:
+            return messages
+
+        # We need to identify all tool_use/tool_result relationships
+        # First, find all AIMessage+ToolMessage pairs
+        pairs = []
+        i = 0
+        while i < len(messages) - 1:
+            if is_tool_pair(messages[i], messages[i + 1]):
+                pairs.append((i, i + 1))
+                i += 2
+            else:
+                i += 1
+
+        # For Anthropic, we need to ensure that:
+        # 1. If we include an AIMessage with tool_use, we must include the following ToolMessage
+        # 2. If we include a ToolMessage, we must include the preceding AIMessage with tool_use
+
+        # The safest approach is to always keep complete AIMessage+ToolMessage pairs together
+        # First, identify all complete pairs
+        complete_pairs = []
+        for start, end in pairs:
+            complete_pairs.append((start, end))
+
+        # Now we'll build our result, starting with the kept_messages
+        # But we need to be careful about the first message if it has tool_use
+        result = []
+
+        # Check if the last message in kept_messages has tool_use
+        if (
+            kept_messages
+            and isinstance(kept_messages[-1], AIMessage)
+            and has_tool_use(kept_messages[-1])
+        ):
+            # We need to find the corresponding ToolMessage
+            for i, (ai_idx, tool_idx) in enumerate(pairs):
+                if messages[ai_idx] is kept_messages[-1]:
+                    # Found the pair, add all kept_messages except the last one
+                    result.extend(kept_messages[:-1])
+                    # Add the AIMessage and ToolMessage as a pair
+                    result.extend([messages[ai_idx], messages[tool_idx]])
+                    # Remove this pair from the list of pairs to process later
+                    pairs = pairs[:i] + pairs[i + 1 :]
+                    break
+            else:
+                # If we didn't find a matching pair, just add all kept_messages
+                result.extend(kept_messages)
+        else:
+            # No tool_use in the last kept message, just add all kept_messages
+            result.extend(kept_messages)
+
+        # If we're using the "last" strategy, we'll try to include pairs from the end
+        if strategy == "last":
+            # First collect all pairs we can include within the token limit
+            pairs_to_include = []
+
+            # Process pairs from the end (newest first)
+            for pair_idx, (ai_idx, tool_idx) in enumerate(reversed(complete_pairs)):
+                # Try adding this pair
+                test_msgs = result.copy()
+
+                # Add all previously selected pairs
+                for prev_ai_idx, prev_tool_idx in pairs_to_include:
+                    test_msgs.extend([messages[prev_ai_idx], messages[prev_tool_idx]])
+
+                # Add this pair
+                test_msgs.extend([messages[ai_idx], messages[tool_idx]])
+
+                if token_counter(test_msgs) <= max_tokens:
+                    # This pair fits, add it to our list
+                    pairs_to_include.append((ai_idx, tool_idx))
+                else:
+                    # This pair would exceed the token limit
+                    break
+
+            # Now add the pairs in the correct order
+            # Sort by index to maintain the original conversation flow
+            pairs_to_include.sort(key=lambda x: x[0])
+            for ai_idx, tool_idx in pairs_to_include:
+                result.extend([messages[ai_idx], messages[tool_idx]])
+
+        # No need to sort - we've already added messages in the correct order
+
+        return result
+
+    # If no tool_use, proceed with normal segmentation
+    segments = []
+    i = 0
+
+    # Group messages into segments
+    while i < len(remaining_msgs):
+        segments.append([remaining_msgs[i]])
+        i += 1
+
+    # Now we have segments that maintain the required structure
+    # We'll add segments from the end (for "last" strategy) or beginning (for "first")
+    # until we hit the token limit
+
+    if strategy == "last":
+        # If we have no segments, just return kept_messages
+        if not segments:
+            return kept_messages
+
+        result = []
+
+        # Process segments from the end
+        for i, segment in enumerate(reversed(segments)):
+            # Try adding this segment
+            test_msgs = segment + result
+
+            if token_counter(kept_messages + test_msgs) <= max_tokens:
+                result = segment + result
+            else:
+                # This segment would exceed the token limit
+                break
+
+        final_result = kept_messages + result
+
+        # For Anthropic, we need to ensure the conversation follows a valid structure
+        # We'll do a final check of the entire conversation
+
+        # Validate the conversation structure
+        valid_result = []
+        i = 0
+
+        # Process messages in order
+        while i < len(final_result):
+            current_msg = final_result[i]
+
+            # If this is an AIMessage with tool_use, it must be followed by a ToolMessage
+            if (
+                i < len(final_result) - 1
+                and isinstance(current_msg, AIMessage)
+                and has_tool_use(current_msg)
+            ):
+                if isinstance(final_result[i + 1], ToolMessage):
+                    # This is a valid tool_use + tool_result pair
+                    valid_result.append(current_msg)
+                    valid_result.append(final_result[i + 1])
+                    i += 2
+                else:
+                    # Invalid: AIMessage with tool_use not followed by ToolMessage
+                    # Skip this message to maintain valid structure
+                    i += 1
+            else:
+                # Regular message, just add it
+                valid_result.append(current_msg)
+                i += 1
+
+        # Final check: don't end with an AIMessage that has tool_use
+        if (
+            valid_result
+            and isinstance(valid_result[-1], AIMessage)
+            and has_tool_use(valid_result[-1])
+        ):
+            valid_result.pop()  # Remove the last message
+
+        return valid_result
+
+    elif strategy == "first":
+        result = []
+
+        # Process segments from the beginning
+        for i, segment in enumerate(segments):
+            # Try adding this segment
+            test_msgs = result + segment
+            if token_counter(kept_messages + test_msgs) <= max_tokens:
+                result = result + segment
+            else:
+                # This segment would exceed the token limit
+                break
+
+        final_result = kept_messages + result
+
+        return final_result
diff --git a/ra_aid/anthropic_token_limiter.py b/ra_aid/anthropic_token_limiter.py
new file mode 100644
index 0000000..45a79d4
--- /dev/null
+++ b/ra_aid/anthropic_token_limiter.py
@@ -0,0 +1,236 @@
+"""Utilities for handling token limits with Anthropic models."""
+
+from functools import partial
+from typing import Any, Dict, List, Optional, Sequence
+from dataclasses import dataclass
+
+from langchain_anthropic import ChatAnthropic
+from langchain_core.messages import (
+    AIMessage,
+    BaseMessage,
+    RemoveMessage,
+    ToolMessage,
+    trim_messages,
+)
+from langchain_core.messages.base import message_to_dict
+
+from ra_aid.anthropic_message_utils import (
+    anthropic_trim_messages,
+    has_tool_use,
+)
+from langgraph.prebuilt.chat_agent_executor import AgentState
+from litellm import token_counter
+
+from ra_aid.agent_backends.ciayn_agent import CiaynAgent
+from ra_aid.database.repositories.config_repository import get_config_repository
+from ra_aid.logging_config import get_logger
+from ra_aid.models_params import DEFAULT_TOKEN_LIMIT, models_params
+from ra_aid.console.output import cpm, print_messages_compact
+
+logger = get_logger(__name__)
+
+
+def estimate_messages_tokens(messages: Sequence[BaseMessage]) -> int:
+    """Helper function to estimate total tokens in a sequence of messages.
+
+    Args:
+        messages: Sequence of messages to count tokens for
+
+    Returns:
+        Total estimated token count
+    """
+    if not messages:
+        return 0
+
+    estimate_tokens = CiaynAgent._estimate_tokens
+    return sum(estimate_tokens(msg) for msg in messages)
+
+
+def convert_message_to_litellm_format(message: BaseMessage) -> Dict:
+    """Convert a BaseMessage to the format expected by litellm.
+
+    Args:
+        message: The BaseMessage to convert
+
+    Returns:
+        Dict in litellm format
+    """
+    message_dict = message_to_dict(message)
+    return {
+        "role": message_dict["type"],
+        "content": message_dict["data"]["content"],
+    }
+
+
+def create_token_counter_wrapper(model: str):
+    """Create a wrapper for token counter that handles BaseMessage conversion.
+
+    Args:
+        model: The model name to use for token counting
+
+    Returns:
+        A function that accepts BaseMessage objects and returns token count
+    """
+
+    # Create a partial function that already has the model parameter set
+    base_token_counter = partial(token_counter, model=model)
+
+    def wrapped_token_counter(messages: List[BaseMessage]) -> int:
+        """Count tokens in a list of messages, converting BaseMessage to dict for litellm token counter usage.
+
+        Args:
+            messages: List of BaseMessage objects
+
+        Returns:
+            Token count for the messages
+        """
+        if not messages:
+            return 0
+
+        litellm_messages = [convert_message_to_litellm_format(msg) for msg in messages]
+        result = base_token_counter(messages=litellm_messages)
+        return result
+
+    return wrapped_token_counter
+
+
+def state_modifier(
+    state: AgentState, model: ChatAnthropic, max_input_tokens: int = DEFAULT_TOKEN_LIMIT
+) -> list[BaseMessage]:
+    """Given the agent state and max_tokens, return a trimmed list of messages.
+
+    This uses anthropic_trim_messages which always keeps the first 2 messages.
+
+    Args:
+        state: The current agent state containing messages
+        model: The language model to use for token counting
+        max_input_tokens: Maximum number of tokens to allow (default: DEFAULT_TOKEN_LIMIT)
+
+    Returns:
+        list[BaseMessage]: Trimmed list of messages that fits within token limit
+    """
+
+    messages = state["messages"]
+    if not messages:
+        return []
+
+    wrapped_token_counter = create_token_counter_wrapper(model.model)
+
+    result = anthropic_trim_messages(
+        messages,
+        token_counter=wrapped_token_counter,
+        max_tokens=max_input_tokens,
+        strategy="last",
+        allow_partial=False,
+        include_system=True,
+        num_messages_to_keep=2,
+    )
+
+    if len(result) < len(messages):
+        logger.info(f"Anthropic Token Limiter Trimmed: {len(messages)} messages → {len(result)} messages")
+
+    return result
+
+
+def sonnet_35_state_modifier(
+    state: AgentState, max_input_tokens: int = DEFAULT_TOKEN_LIMIT
+) -> list[BaseMessage]:
+    """Given the agent state and max_tokens, return a trimmed list of messages.
+
+    Args:
+        state: The current agent state containing messages
+        max_tokens: Maximum number of tokens to allow (default: DEFAULT_TOKEN_LIMIT)
+
+    Returns:
+        list[BaseMessage]: Trimmed list of messages that fits within token limit
+    """
+    messages = state["messages"]
+
+    if not messages:
+        return []
+
+    first_message = messages[0]
+    remaining_messages = messages[1:]
+    first_tokens = estimate_messages_tokens([first_message])
+    new_max_tokens = max_input_tokens - first_tokens
+
+    trimmed_remaining = trim_messages(
+        remaining_messages,
+        token_counter=estimate_messages_tokens,
+        max_tokens=new_max_tokens,
+        strategy="last",
+        allow_partial=False,
+        include_system=True,
+    )
+
+    result = [first_message] + trimmed_remaining
+
+    return result
+
+
+def get_model_token_limit(
+    config: Dict[str, Any], agent_type: str = "default"
+) -> Optional[int]:
+    """Get the token limit for the current model configuration based on agent type.
+
+    Args:
+        config: Configuration dictionary containing provider and model information
+        agent_type: Type of agent ("default", "research", or "planner")
+
+    Returns:
+        Optional[int]: The token limit if found, None otherwise
+    """
+    try:
+        # Try to get config from repository for production use
+        try:
+            config_from_repo = get_config_repository().get_all()
+            # If we succeeded, use the repository config instead of passed config
+            config = config_from_repo
+        except RuntimeError:
+            # In tests, this may fail because the repository isn't set up
+            # So we'll use the passed config directly
+            pass
+        if agent_type == "research":
+            provider = config.get("research_provider", "") or config.get("provider", "")
+            model_name = config.get("research_model", "") or config.get("model", "")
+        elif agent_type == "planner":
+            provider = config.get("planner_provider", "") or config.get("provider", "")
+            model_name = config.get("planner_model", "") or config.get("model", "")
+        else:
+            provider = config.get("provider", "")
+            model_name = config.get("model", "")
+
+        try:
+            from litellm import get_model_info
+
+            provider_model = model_name if not provider else f"{provider}/{model_name}"
+            model_info = get_model_info(provider_model)
+            max_input_tokens = model_info.get("max_input_tokens")
+            if max_input_tokens:
+                logger.debug(
+                    f"Using litellm token limit for {model_name}: {max_input_tokens}"
+                )
+                return max_input_tokens
+        except Exception as e:
+            logger.debug(
+                f"Error getting model info from litellm: {e}, falling back to models_params"
+            )
+
+        # Fallback to models_params dict
+        # Normalize model name for fallback lookup (e.g. claude-2 -> claude2)
+        normalized_name = model_name.replace("-", "")
+        provider_tokens = models_params.get(provider, {})
+        if normalized_name in provider_tokens:
+            max_input_tokens = provider_tokens[normalized_name]["token_limit"]
+            logger.debug(
+                f"Found token limit for {provider}/{model_name}: {max_input_tokens}"
+            )
+        else:
+            max_input_tokens = None
+            logger.debug(f"Could not find token limit for {provider}/{model_name}")
+
+        return max_input_tokens
+
+    except Exception as e:
+        logger.warning(f"Failed to get model token limit: {e}")
+        return None
diff --git a/ra_aid/config.py b/ra_aid/config.py
index 936fc26..47afde7 100644
--- a/ra_aid/config.py
+++ b/ra_aid/config.py
@@ -6,6 +6,7 @@ DEFAULT_MAX_TOOL_FAILURES = 3
 FALLBACK_TOOL_MODEL_LIMIT = 5
 RETRY_FALLBACK_COUNT = 3
 DEFAULT_TEST_CMD_TIMEOUT = 60 * 5  # 5 minutes in seconds
+DEFAULT_MODEL="claude-3-7-sonnet-20250219"
 DEFAULT_SHOW_COST = False
 
 
@@ -16,4 +17,4 @@ VALID_PROVIDERS = [
     "openai-compatible",
     "deepseek",
     "gemini",
-]
\ No newline at end of file
+]
diff --git a/ra_aid/console/output.py b/ra_aid/console/output.py
index 68b0b85..b45aeba 100644
--- a/ra_aid/console/output.py
+++ b/ra_aid/console/output.py
@@ -1,6 +1,6 @@
-from typing import Any, Dict, Literal, Optional
+from typing import Any, Dict, List, Literal, Optional, Sequence
 
-from langchain_core.messages import AIMessage
+from langchain_core.messages import AIMessage, BaseMessage, HumanMessage
 from rich.markdown import Markdown
 from rich.panel import Panel
 
@@ -98,3 +98,57 @@ def cpm(message: str, title: Optional[str] = None, border_style: str = "blue") -
     """
 
     console.print(Panel(Markdown(message), title=title, border_style=border_style))
+
+
+def print_messages_compact(messages: Sequence[BaseMessage]) -> None:
+    """Print a compact representation of a list of messages.
+
+    Warning: Used mainly for debugging purposes so do not delete if not referenced anywhere!
+    For all message types, only the first 30 characters of content are shown.
+
+    Args:
+        messages: A sequence of BaseMessage objects to print
+    """
+    if not messages:
+        console.print("[italic]No messages[/italic]")
+        return
+
+    for i, msg in enumerate(messages):
+        msg_type = msg.__class__.__name__
+        content = msg.content
+        
+        # Process content based on its type
+        if isinstance(content, str):
+            display_content = f"{content[:30]}..." if len(content) > 30 else content
+        elif isinstance(content, list):
+            # Handle structured content (list of content blocks)
+            content_preview = []
+            for item in content[:2]:  # Show first 2 items at most
+                if isinstance(item, dict):
+                    if item.get("type") == "text":
+                        text = item.get("text", "")
+                        content_preview.append(f"text: {text[:20]}..." if len(text) > 20 else f"text: {text}")
+                    elif item.get("type") == "tool_call":
+                        tool_name = item.get("tool_call", {}).get("name", "unknown")
+                        content_preview.append(f"tool_call: {tool_name}")
+                    else:
+                        content_preview.append(f"{item.get('type', 'unknown')}")
+            
+            if len(content) > 2:
+                content_preview.append(f"...({len(content)-2} more)")
+                
+            display_content = ", ".join(content_preview)
+        else:
+            display_content = str(content)[:30] + "..." if len(str(content)) > 30 else str(content)
+
+        # Add additional tool message info if available
+        additional_info = []
+        if hasattr(msg, "tool_call_id") and msg.tool_call_id:
+            additional_info.append(f"tool_call_id: {msg.tool_call_id}")
+        if hasattr(msg, "name") and msg.name:
+            additional_info.append(f"name: {msg.name}")
+        if hasattr(msg, "status") and msg.status:
+            additional_info.append(f"status: {msg.status}")
+            
+        info_str = f" ({', '.join(additional_info)})" if additional_info else ""
+        console.print(f"[{i}] [bold]{msg_type}{info_str}[/bold]: {display_content}")
diff --git a/ra_aid/llm.py b/ra_aid/llm.py
index 2ad07f4..56ec811 100644
--- a/ra_aid/llm.py
+++ b/ra_aid/llm.py
@@ -259,8 +259,9 @@ def create_llm_client(
     else:
         temp_kwargs = {}
 
+    thinking_kwargs = {}
     if supports_thinking:
-        temp_kwargs = {"thinking": {"type": "enabled", "budget_tokens": 12000}}
+        thinking_kwargs = {"thinking": {"type": "enabled", "budget_tokens": 12000}}
 
     if provider == "deepseek":
         return create_deepseek_client(
@@ -268,6 +269,7 @@ def create_llm_client(
             api_key=config["api_key"],
             base_url=config["base_url"],
             **temp_kwargs,
+            **thinking_kwargs,
             is_expert=is_expert,
         )
     elif provider == "openrouter":
@@ -275,6 +277,7 @@ def create_llm_client(
             model_name=model_name,
             api_key=config["api_key"],
             **temp_kwargs,
+            **thinking_kwargs,
             is_expert=is_expert,
         )
     elif provider == "openai":
@@ -301,6 +304,7 @@ def create_llm_client(
             max_retries=LLM_MAX_RETRIES,
             max_tokens=model_config.get("max_tokens", 64000),
             **temp_kwargs,
+            **thinking_kwargs,
         )
     elif provider == "openai-compatible":
         return ChatOpenAI(
@@ -310,6 +314,7 @@ def create_llm_client(
             timeout=LLM_REQUEST_TIMEOUT,
             max_retries=LLM_MAX_RETRIES,
             **temp_kwargs,
+            **thinking_kwargs,
         )
     elif provider == "gemini":
         return ChatGoogleGenerativeAI(
@@ -318,6 +323,7 @@ def create_llm_client(
             timeout=LLM_REQUEST_TIMEOUT,
             max_retries=LLM_MAX_RETRIES,
             **temp_kwargs,
+            **thinking_kwargs,
         )
     else:
         raise ValueError(f"Unsupported provider: {provider}")
diff --git a/ra_aid/tools/agent.py b/ra_aid/tools/agent.py
index e066690..740ba80 100644
--- a/ra_aid/tools/agent.py
+++ b/ra_aid/tools/agent.py
@@ -14,8 +14,9 @@ from ra_aid.agent_context import (
     is_crashed,
     reset_completion_flags,
 )
+from ra_aid.config import DEFAULT_MODEL
 from ra_aid.console.formatting import print_error, print_task_header
-from ra_aid.database.repositories.human_input_repository import HumanInputRepository, get_human_input_repository
+from ra_aid.database.repositories.human_input_repository import get_human_input_repository
 from ra_aid.database.repositories.key_fact_repository import get_key_fact_repository
 from ra_aid.database.repositories.key_snippet_repository import get_key_snippet_repository
 from ra_aid.database.repositories.config_repository import get_config_repository
@@ -385,7 +386,7 @@ def request_task_implementation(task_spec: str) -> str:
     config = get_config_repository().get_all()
     model = initialize_llm(
         config.get("provider", "anthropic"),
-        config.get("model", "claude-3-5-sonnet-20241022"),
+        config.get("model",DEFAULT_MODEL),
         temperature=config.get("temperature"),
     )
 
@@ -552,7 +553,7 @@ def request_implementation(task_spec: str) -> str:
     config = get_config_repository().get_all()
     model = initialize_llm(
         config.get("provider", "anthropic"),
-        config.get("model", "claude-3-5-sonnet-20241022"),
+        config.get("model", DEFAULT_MODEL),
         temperature=config.get("temperature"),
     )
 
@@ -685,4 +686,4 @@ def request_implementation(task_spec: str) -> str:
     # Join all parts into a single markdown string
     markdown_output = "".join(markdown_parts)
 
-    return markdown_output
\ No newline at end of file
+    return markdown_output
diff --git a/tests/ra_aid/test_agent_utils.py b/tests/ra_aid/test_agent_utils.py
index 13739c8..ff978a8 100644
--- a/tests/ra_aid/test_agent_utils.py
+++ b/tests/ra_aid/test_agent_utils.py
@@ -14,12 +14,18 @@ from ra_aid.agent_context import (
 from ra_aid.agent_utils import (
     AgentState,
     create_agent,
-    get_model_token_limit,
     is_anthropic_claude,
+)
+from ra_aid.anthropic_token_limiter import (
+    get_model_token_limit,
     state_modifier,
 )
 from ra_aid.models_params import DEFAULT_TOKEN_LIMIT, models_params
-from ra_aid.database.repositories.config_repository import ConfigRepositoryManager, get_config_repository, config_repo_var
+from ra_aid.database.repositories.config_repository import (
+    ConfigRepositoryManager,
+    get_config_repository,
+    config_repo_var,
+)
 
 
 @pytest.fixture
@@ -32,154 +38,91 @@ def mock_model():
 @pytest.fixture
 def mock_config_repository():
     """Mock the ConfigRepository to avoid database operations during tests"""
-    with patch('ra_aid.database.repositories.config_repository.config_repo_var') as mock_repo_var:
+    with patch(
+        "ra_aid.database.repositories.config_repository.config_repo_var"
+    ) as mock_repo_var:
         # Setup a mock repository
         mock_repo = MagicMock()
-        
+
         # Create a dictionary to simulate config
         config = {}
-        
+
         # Setup get method to return config values
         def get_config(key, default=None):
             return config.get(key, default)
+
         mock_repo.get.side_effect = get_config
-        
+
         # Setup get_all method to return all config values
         mock_repo.get_all.return_value = config
-        
+
         # Setup set method to update config values
         def set_config(key, value):
             config[key] = value
+
         mock_repo.set.side_effect = set_config
-        
+
         # Setup update method to update multiple config values
         def update_config(update_dict):
             config.update(update_dict)
+
         mock_repo.update.side_effect = update_config
-        
+
         # Make the mock context var return our mock repo
         mock_repo_var.get.return_value = mock_repo
-        
+
         yield mock_repo
 
 
 @pytest.fixture(autouse=True)
 def mock_trajectory_repository():
     """Mock the TrajectoryRepository to avoid database operations during tests"""
-    with patch('ra_aid.database.repositories.trajectory_repository.trajectory_repo_var') as mock_repo_var:
+    with patch(
+        "ra_aid.database.repositories.trajectory_repository.trajectory_repo_var"
+    ) as mock_repo_var:
         # Setup a mock repository
         mock_repo = MagicMock()
-        
+
         # Setup create method to return a mock trajectory
         def mock_create(**kwargs):
             mock_trajectory = MagicMock()
             mock_trajectory.id = 1
             return mock_trajectory
+
         mock_repo.create.side_effect = mock_create
-        
+
         # Make the mock context var return our mock repo
         mock_repo_var.get.return_value = mock_repo
-        
+
         yield mock_repo
 
 
 @pytest.fixture(autouse=True)
 def mock_human_input_repository():
     """Mock the HumanInputRepository to avoid database operations during tests"""
-    with patch('ra_aid.database.repositories.human_input_repository.human_input_repo_var') as mock_repo_var:
+    with patch(
+        "ra_aid.database.repositories.human_input_repository.human_input_repo_var"
+    ) as mock_repo_var:
         # Setup a mock repository
         mock_repo = MagicMock()
-        
+
         # Setup get_most_recent_id method to return a dummy ID
         mock_repo.get_most_recent_id.return_value = 1
-        
+
         # Make the mock context var return our mock repo
         mock_repo_var.get.return_value = mock_repo
-        
+
         yield mock_repo
 
 
-def test_get_model_token_limit_anthropic(mock_config_repository):
-    """Test get_model_token_limit with Anthropic model."""
-    config = {"provider": "anthropic", "model": "claude2"}
-    mock_config_repository.update(config)
-
-    token_limit = get_model_token_limit(config, "default")
-    assert token_limit == models_params["anthropic"]["claude2"]["token_limit"]
-
-
-def test_get_model_token_limit_openai(mock_config_repository):
-    """Test get_model_token_limit with OpenAI model."""
-    config = {"provider": "openai", "model": "gpt-4"}
-    mock_config_repository.update(config)
-
-    token_limit = get_model_token_limit(config, "default")
-    assert token_limit == models_params["openai"]["gpt-4"]["token_limit"]
-
-
-def test_get_model_token_limit_unknown(mock_config_repository):
-    """Test get_model_token_limit with unknown provider/model."""
-    config = {"provider": "unknown", "model": "unknown-model"}
-    mock_config_repository.update(config)
-
-    token_limit = get_model_token_limit(config, "default")
-    assert token_limit is None
-
-
-def test_get_model_token_limit_missing_config(mock_config_repository):
-    """Test get_model_token_limit with missing configuration."""
-    config = {}
-    mock_config_repository.update(config)
-
-    token_limit = get_model_token_limit(config, "default")
-    assert token_limit is None
-
-
-def test_get_model_token_limit_litellm_success():
-    """Test get_model_token_limit successfully getting limit from litellm."""
-    config = {"provider": "anthropic", "model": "claude-2"}
-
-    with patch("ra_aid.agent_utils.get_model_info") as mock_get_info:
-        mock_get_info.return_value = {"max_input_tokens": 100000}
-        token_limit = get_model_token_limit(config, "default")
-        assert token_limit == 100000
-
-
-def test_get_model_token_limit_litellm_not_found():
-    """Test fallback to models_tokens when litellm raises NotFoundError."""
-    config = {"provider": "anthropic", "model": "claude-2"}
-
-    with patch("ra_aid.agent_utils.get_model_info") as mock_get_info:
-        mock_get_info.side_effect = litellm.exceptions.NotFoundError(
-            message="Model not found", model="claude-2", llm_provider="anthropic"
-        )
-        token_limit = get_model_token_limit(config, "default")
-        assert token_limit == models_params["anthropic"]["claude2"]["token_limit"]
-
-
-def test_get_model_token_limit_litellm_error():
-    """Test fallback to models_tokens when litellm raises other exceptions."""
-    config = {"provider": "anthropic", "model": "claude-2"}
-
-    with patch("ra_aid.agent_utils.get_model_info") as mock_get_info:
-        mock_get_info.side_effect = Exception("Unknown error")
-        token_limit = get_model_token_limit(config, "default")
-        assert token_limit == models_params["anthropic"]["claude2"]["token_limit"]
-
-
-def test_get_model_token_limit_unexpected_error():
-    """Test returning None when unexpected errors occur."""
-    config = None  # This will cause an attribute error when accessed
-
-    token_limit = get_model_token_limit(config, "default")
-    assert token_limit is None
-
-
 def test_create_agent_anthropic(mock_model, mock_config_repository):
     """Test create_agent with Anthropic Claude model."""
     mock_config_repository.update({"provider": "anthropic", "model": "claude-2"})
 
-    with patch("ra_aid.agent_utils.create_react_agent") as mock_react:
+    with (
+        patch("ra_aid.agent_utils.create_react_agent") as mock_react,
+        patch("ra_aid.anthropic_token_limiter.state_modifier") as mock_state_modifier,
+    ):
         mock_react.return_value = "react_agent"
         agent = create_agent(mock_model, [])
 
@@ -187,9 +130,10 @@ def test_create_agent_anthropic(mock_model, mock_config_repository):
         mock_react.assert_called_once_with(
             mock_model,
             [],
-            interrupt_after=['tools'],
+            interrupt_after=["tools"],
             version="v2",
             state_modifier=mock_react.call_args[1]["state_modifier"],
+            name="React",
         )
 
 
@@ -257,20 +201,7 @@ def mock_messages():
     ]
 
 
-def test_state_modifier(mock_messages):
-    """Test that state_modifier correctly trims recent messages while preserving the first message when total tokens > max_tokens."""
-    state = AgentState(messages=mock_messages)
-
-    with patch(
-        "ra_aid.agent_backends.ciayn_agent.CiaynAgent._estimate_tokens"
-    ) as mock_estimate:
-        mock_estimate.side_effect = lambda msg: 100 if msg else 0
-
-        result = state_modifier(state, max_input_tokens=250)
-
-        assert len(result) < len(mock_messages)
-        assert isinstance(result[0], SystemMessage)
-        assert result[-1] == mock_messages[-1]
+# This test has been moved to test_anthropic_token_limiter.py
 
 
 def test_create_agent_with_checkpointer(mock_model, mock_config_repository):
@@ -291,17 +222,21 @@ def test_create_agent_with_checkpointer(mock_model, mock_config_repository):
         )
 
 
-def test_create_agent_anthropic_token_limiting_enabled(mock_model, mock_config_repository):
+def test_create_agent_anthropic_token_limiting_enabled(
+    mock_model, mock_config_repository
+):
     """Test create_agent sets up token limiting for Claude models when enabled."""
-    mock_config_repository.update({
-        "provider": "anthropic",
-        "model": "claude-2",
-        "limit_tokens": True,
-    })
+    mock_config_repository.update(
+        {
+            "provider": "anthropic",
+            "model": "claude-2",
+            "limit_tokens": True,
+        }
+    )
 
     with (
         patch("ra_aid.agent_utils.create_react_agent") as mock_react,
-        patch("ra_aid.agent_utils.get_model_token_limit") as mock_limit,
+        patch("ra_aid.anthropic_token_limiter.get_model_token_limit") as mock_limit,
     ):
         mock_react.return_value = "react_agent"
         mock_limit.return_value = 100000
@@ -314,17 +249,21 @@ def test_create_agent_anthropic_token_limiting_enabled(mock_model, mock_config_r
         assert callable(args[1]["state_modifier"])
 
 
-def test_create_agent_anthropic_token_limiting_disabled(mock_model, mock_config_repository):
+def test_create_agent_anthropic_token_limiting_disabled(
+    mock_model, mock_config_repository
+):
     """Test create_agent doesn't set up token limiting for Claude models when disabled."""
-    mock_config_repository.update({
-        "provider": "anthropic",
-        "model": "claude-2",
-        "limit_tokens": False,
-    })
+    mock_config_repository.update(
+        {
+            "provider": "anthropic",
+            "model": "claude-2",
+            "limit_tokens": False,
+        }
+    )
 
     with (
         patch("ra_aid.agent_utils.create_react_agent") as mock_react,
-        patch("ra_aid.agent_utils.get_model_token_limit") as mock_limit,
+        patch("ra_aid.anthropic_token_limiter.get_model_token_limit") as mock_limit,
     ):
         mock_react.return_value = "react_agent"
         mock_limit.return_value = 100000
@@ -332,39 +271,12 @@ def test_create_agent_anthropic_token_limiting_disabled(mock_model, mock_config_
         agent = create_agent(mock_model, [])
 
         assert agent == "react_agent"
-        mock_react.assert_called_once_with(mock_model, [], interrupt_after=['tools'], version="v2")
+        mock_react.assert_called_once_with(
+            mock_model, [], interrupt_after=["tools"], version="v2", name="React"
+        )
 
 
-def test_get_model_token_limit_research(mock_config_repository):
-    """Test get_model_token_limit with research provider and model."""
-    config = {
-        "provider": "openai",
-        "model": "gpt-4",
-        "research_provider": "anthropic",
-        "research_model": "claude-2",
-    }
-    mock_config_repository.update(config)
-    
-    with patch("ra_aid.agent_utils.get_model_info") as mock_get_info:
-        mock_get_info.return_value = {"max_input_tokens": 150000}
-        token_limit = get_model_token_limit(config, "research")
-        assert token_limit == 150000
-
-
-def test_get_model_token_limit_planner(mock_config_repository):
-    """Test get_model_token_limit with planner provider and model."""
-    config = {
-        "provider": "openai",
-        "model": "gpt-4",
-        "planner_provider": "deepseek",
-        "planner_model": "dsm-1",
-    }
-    mock_config_repository.update(config)
-    
-    with patch("ra_aid.agent_utils.get_model_info") as mock_get_info:
-        mock_get_info.return_value = {"max_input_tokens": 120000}
-        token_limit = get_model_token_limit(config, "planner")
-        assert token_limit == 120000
+# These tests have been moved to test_anthropic_token_limiter.py
 
 
 # New tests for private helper methods in agent_utils.py
@@ -396,11 +308,11 @@ def test_agent_context_depth():
     with agent_context() as ctx1:
         assert get_depth() == 0  # Root context has depth 0
         assert ctx1.depth == 0
-        
+
         with agent_context() as ctx2:
             assert get_depth() == 1  # Nested context has depth 1
             assert ctx2.depth == 1
-            
+
             with agent_context() as ctx3:
                 assert get_depth() == 2  # Doubly nested context has depth 2
                 assert ctx3.depth == 2
@@ -418,7 +330,7 @@ def test_run_agent_stream(monkeypatch, mock_config_repository):
     class DummyAgent:
         def stream(self, input_data, cfg: dict):
             yield {"content": "chunk1"}
-            
+
         def get_state(self, state_config=None):
             # Return an object with a next property set to None
             return State()
@@ -469,28 +381,28 @@ def test_handle_api_error_valueerror():
     # ValueError not containing "code" or rate limit phrases should be re-raised
     with pytest.raises(ValueError):
         _handle_api_error(ValueError("some unrelated error"), 0, 5, 1)
-        
+
     # ValueError with "429" should be handled without raising
     _handle_api_error(ValueError("error code 429"), 0, 5, 1)
-    
+
     # ValueError with "rate limit" phrase should be handled without raising
     _handle_api_error(ValueError("hit rate limit"), 0, 5, 1)
-    
+
     # ValueError with "too many requests" phrase should be handled without raising
     _handle_api_error(ValueError("too many requests, try later"), 0, 5, 1)
-    
+
     # ValueError with "quota exceeded" phrase should be handled without raising
     _handle_api_error(ValueError("quota exceeded for this month"), 0, 5, 1)
 
 
 def test_handle_api_error_status_code():
     from ra_aid.agent_utils import _handle_api_error
-    
+
     # Error with status_code=429 attribute should be handled without raising
     error_with_status = Exception("Rate limited")
     error_with_status.status_code = 429
     _handle_api_error(error_with_status, 0, 5, 1)
-    
+
     # Error with http_status=429 attribute should be handled without raising
     error_with_http_status = Exception("Too many requests")
     error_with_http_status.http_status = 429
@@ -499,16 +411,16 @@ def test_handle_api_error_status_code():
 
 def test_handle_api_error_rate_limit_phrases():
     from ra_aid.agent_utils import _handle_api_error
-    
+
     # Generic exception with "rate limit" phrase should be handled without raising
     _handle_api_error(Exception("You have exceeded your rate limit"), 0, 5, 1)
-    
+
     # Generic exception with "too many requests" phrase should be handled without raising
     _handle_api_error(Exception("Too many requests, please slow down"), 0, 5, 1)
-    
+
     # Generic exception with "quota exceeded" phrase should be handled without raising
     _handle_api_error(Exception("API quota exceeded for this billing period"), 0, 5, 1)
-    
+
     # Generic exception with "rate" and "limit" separate but in message should be handled
     _handle_api_error(Exception("You hit the rate at which we limit requests"), 0, 5, 1)
 
@@ -629,7 +541,9 @@ def test_run_agent_with_retry_checks_crash_status(monkeypatch, mock_config_repos
         assert "Agent has crashed: Test crash message" in result
 
 
-def test_run_agent_with_retry_handles_badrequest_error(monkeypatch, mock_config_repository):
+def test_run_agent_with_retry_handles_badrequest_error(
+    monkeypatch, mock_config_repository
+):
     """Test that run_agent_with_retry properly handles BadRequestError as unretryable."""
     from ra_aid.agent_context import agent_context, is_crashed
     from ra_aid.agent_utils import run_agent_with_retry
@@ -687,7 +601,9 @@ def test_run_agent_with_retry_handles_badrequest_error(monkeypatch, mock_config_
         assert is_crashed()
 
 
-def test_run_agent_with_retry_handles_api_badrequest_error(monkeypatch, mock_config_repository):
+def test_run_agent_with_retry_handles_api_badrequest_error(
+    monkeypatch, mock_config_repository
+):
     """Test that run_agent_with_retry properly handles API BadRequestError as unretryable."""
     # Import APIError from anthropic module and patch it on the agent_utils module
 
@@ -758,7 +674,9 @@ def test_run_agent_with_retry_handles_api_badrequest_error(monkeypatch, mock_con
 def test_handle_api_error_resource_exhausted():
     from google.api_core.exceptions import ResourceExhausted
     from ra_aid.agent_utils import _handle_api_error
-    
+
     # ResourceExhausted exception should be handled without raising
-    resource_exhausted_error = ResourceExhausted("429 Resource has been exhausted (e.g. check quota).")
-    _handle_api_error(resource_exhausted_error, 0, 5, 1)
\ No newline at end of file
+    resource_exhausted_error = ResourceExhausted(
+        "429 Resource has been exhausted (e.g. check quota)."
+    )
+    _handle_api_error(resource_exhausted_error, 0, 5, 1)
diff --git a/tests/ra_aid/test_anthropic_token_limiter.py b/tests/ra_aid/test_anthropic_token_limiter.py
new file mode 100644
index 0000000..36f9528
--- /dev/null
+++ b/tests/ra_aid/test_anthropic_token_limiter.py
@@ -0,0 +1,507 @@
+import unittest
+from unittest.mock import MagicMock, patch
+import litellm
+
+from langchain_anthropic import ChatAnthropic
+from langchain_core.messages import (
+    AIMessage, 
+    HumanMessage, 
+    SystemMessage,
+    ToolMessage
+)
+from langgraph.prebuilt.chat_agent_executor import AgentState
+
+from ra_aid.anthropic_token_limiter import (
+    create_token_counter_wrapper,
+    estimate_messages_tokens,
+    get_model_token_limit,
+    state_modifier,
+    sonnet_35_state_modifier,
+    convert_message_to_litellm_format
+)
+from ra_aid.anthropic_message_utils import has_tool_use, is_tool_pair
+from ra_aid.models_params import models_params, DEFAULT_TOKEN_LIMIT
+
+
+class TestAnthropicTokenLimiter(unittest.TestCase):
+    def setUp(self):
+        from ra_aid.config import DEFAULT_MODEL
+        
+        self.mock_model = MagicMock(spec=ChatAnthropic)
+        self.mock_model.model = DEFAULT_MODEL
+        
+        # Sample messages for testing
+        self.system_message = SystemMessage(content="You are a helpful assistant.")
+        self.human_message = HumanMessage(content="Hello, can you help me with a task?")
+        self.ai_message = AIMessage(content="I'd be happy to help! What do you need?")
+        self.long_message = HumanMessage(content="A" * 1000)  # Long message to test trimming
+        
+        # Create more messages for testing
+        self.extra_messages = [
+            HumanMessage(content=f"Extra message {i}") for i in range(5)
+        ]
+        
+        # Mock state for testing state_modifier with many messages
+        self.state = AgentState(
+            messages=[self.system_message, self.human_message, self.long_message] + self.extra_messages,
+            next=None,
+        )
+        
+        # Create tool-related messages for testing
+        self.ai_with_tool_use = AIMessage(
+            content="I'll use a tool to help you",
+            additional_kwargs={"tool_calls": [{"name": "calculator", "input": {"expression": "2+2"}}]}
+        )
+        self.tool_message = ToolMessage(
+            content="4",
+            tool_call_id="tool_call_1",
+            name="calculator"
+        )
+
+    def test_convert_message_to_litellm_format(self):
+        """Test conversion of BaseMessage to litellm format."""
+        # Test human message
+        human_result = convert_message_to_litellm_format(self.human_message)
+        self.assertEqual(human_result["role"], "human")
+        self.assertEqual(human_result["content"], "Hello, can you help me with a task?")
+        
+        # Test system message
+        system_result = convert_message_to_litellm_format(self.system_message)
+        self.assertEqual(system_result["role"], "system")
+        self.assertEqual(system_result["content"], "You are a helpful assistant.")
+        
+        # Test AI message
+        ai_result = convert_message_to_litellm_format(self.ai_message)
+        self.assertEqual(ai_result["role"], "ai")
+        self.assertEqual(ai_result["content"], "I'd be happy to help! What do you need?")
+
+    @patch("ra_aid.anthropic_token_limiter.token_counter")
+    def test_create_token_counter_wrapper(self, mock_token_counter):
+        from ra_aid.config import DEFAULT_MODEL
+        
+        # Setup mock return values
+        mock_token_counter.return_value = 50
+        
+        # Create the wrapper
+        wrapper = create_token_counter_wrapper(DEFAULT_MODEL)
+        
+        # Test with BaseMessage objects
+        result = wrapper([self.human_message])
+        self.assertEqual(result, 50)
+        
+        # Test with empty list
+        result = wrapper([])
+        self.assertEqual(result, 0)
+        
+        # Verify the mock was called with the right parameters
+        mock_token_counter.assert_called_with(messages=unittest.mock.ANY, model=DEFAULT_MODEL)
+
+    @patch("ra_aid.anthropic_token_limiter.CiaynAgent._estimate_tokens")
+    def test_estimate_messages_tokens(self, mock_estimate_tokens):
+        # Setup mock to return different values for different messages
+        mock_estimate_tokens.side_effect = lambda msg: 10 if isinstance(msg, SystemMessage) else 20
+        
+        # Test with multiple messages
+        messages = [self.system_message, self.human_message]
+        result = estimate_messages_tokens(messages)
+        
+        # Should be sum of individual token counts (10 + 20)
+        self.assertEqual(result, 30)
+        
+        # Test with empty list
+        result = estimate_messages_tokens([])
+        self.assertEqual(result, 0)
+
+    @patch("ra_aid.anthropic_token_limiter.create_token_counter_wrapper")
+    @patch("ra_aid.anthropic_token_limiter.print_messages_compact")
+    @patch("ra_aid.anthropic_token_limiter.anthropic_trim_messages")
+    def test_state_modifier(self, mock_trim_messages, mock_print, mock_create_wrapper):
+        # Setup a proper token counter function that returns integers
+        def token_counter(msgs):
+            # Return token count based on number of messages
+            return len(msgs) * 10
+        
+        # Configure the mock to return our token counter
+        mock_create_wrapper.return_value = token_counter
+        
+        # Configure anthropic_trim_messages to return a subset of messages
+        mock_trim_messages.return_value = [self.system_message, self.human_message]
+        
+        # Call state_modifier with a max token limit of 50
+        result = state_modifier(self.state, self.mock_model, max_input_tokens=50)
+        
+        # Should return what anthropic_trim_messages returned
+        self.assertEqual(result, [self.system_message, self.human_message])
+        
+        # Verify the wrapper was created with the right model
+        mock_create_wrapper.assert_called_with(self.mock_model.model)
+        
+        # Verify anthropic_trim_messages was called with the right parameters
+        mock_trim_messages.assert_called_once()
+        
+
+    def test_state_modifier_with_messages(self):
+        """Test that state_modifier correctly trims recent messages while preserving the first message when total tokens > max_tokens."""
+        # Create a state with messages
+        messages = [
+            SystemMessage(content="System prompt"),
+            HumanMessage(content="Human message 1"),
+            AIMessage(content="AI response 1"),
+            HumanMessage(content="Human message 2"),
+            AIMessage(content="AI response 2"),
+        ]
+        state = AgentState(messages=messages)
+        model = MagicMock(spec=ChatAnthropic)
+        model.model = "claude-3-opus-20240229"
+
+        with patch("ra_aid.anthropic_token_limiter.create_token_counter_wrapper") as mock_wrapper, \
+             patch("ra_aid.anthropic_token_limiter.anthropic_trim_messages") as mock_trim, \
+             patch("ra_aid.anthropic_token_limiter.print_messages_compact"):
+            # Setup mock to return a fixed token count per message
+            mock_wrapper.return_value = lambda msgs: len(msgs) * 100
+            # Setup mock to return a subset of messages
+            mock_trim.return_value = [messages[0], messages[-2], messages[-1]]
+            
+            result = state_modifier(state, model, max_input_tokens=250)
+            
+            # Should return what anthropic_trim_messages returned
+            self.assertEqual(len(result), 3)
+            self.assertEqual(result[0], messages[0])  # First message preserved
+            self.assertEqual(result[-1], messages[-1])  # Last message preserved
+        
+    def test_sonnet_35_state_modifier(self):
+        """Test the sonnet 35 state modifier function."""
+        # Create a state with messages
+        state = {"messages": [self.system_message, self.human_message, self.ai_message]}
+        
+        # Test with empty messages
+        empty_state = {"messages": []}
+        
+        # Instead of patching trim_messages which has complex internal logic,
+        # we'll directly patch the sonnet_35_state_modifier's call to trim_messages
+        with patch("ra_aid.anthropic_token_limiter.trim_messages") as mock_trim:
+            # Setup mock to return our desired messages
+            mock_trim.return_value = [self.human_message, self.ai_message]
+            
+            # Test with empty messages
+            self.assertEqual(sonnet_35_state_modifier(empty_state), [])
+            
+            # Test with messages under the limit
+            result = sonnet_35_state_modifier(state, max_input_tokens=10000)
+        
+        # Should keep the first message and call trim_messages for the rest
+        self.assertEqual(len(result), 3)
+        self.assertEqual(result[0], self.system_message)
+        self.assertEqual(result[1:], [self.human_message, self.ai_message])
+        
+        # Verify trim_messages was called with the right parameters
+        mock_trim.assert_called_once()
+        # We can check some of the key arguments
+        call_args = mock_trim.call_args[1]
+        # The actual value is based on the token estimation logic, not a hard-coded 9000
+        self.assertIn("max_tokens", call_args)
+        self.assertEqual(call_args["strategy"], "last")
+        self.assertEqual(call_args["strategy"], "last")
+        self.assertEqual(call_args["allow_partial"], False)
+        self.assertEqual(call_args["include_system"], True)
+
+    @patch("ra_aid.anthropic_token_limiter.get_config_repository")
+    @patch("litellm.get_model_info")
+    def test_get_model_token_limit_from_litellm(self, mock_get_model_info, mock_get_config_repo):
+        from ra_aid.config import DEFAULT_MODEL
+        
+        # Setup mocks
+        mock_config = {"provider": "anthropic", "model": DEFAULT_MODEL}
+        mock_get_config_repo.return_value.get_all.return_value = mock_config
+        
+        # Mock litellm's get_model_info to return a token limit
+        mock_get_model_info.return_value = {"max_input_tokens": 100000}
+        
+        # Test getting token limit
+        result = get_model_token_limit(mock_config)
+        self.assertEqual(result, 100000)
+        
+        # Verify get_model_info was called with the right model
+        mock_get_model_info.assert_called_with(f"anthropic/{DEFAULT_MODEL}")
+        
+    def test_get_model_token_limit_research(self):
+        """Test get_model_token_limit with research provider and model."""
+        config = {
+            "provider": "openai",
+            "model": "gpt-4",
+            "research_provider": "anthropic",
+            "research_model": "claude-2",
+        }
+        
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo, \
+             patch("litellm.get_model_info") as mock_get_info:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            mock_get_info.return_value = {"max_input_tokens": 150000}
+            token_limit = get_model_token_limit(config, "research")
+            self.assertEqual(token_limit, 150000)
+            # Verify get_model_info was called with the research model
+            mock_get_info.assert_called_with("anthropic/claude-2")
+
+    def test_get_model_token_limit_planner(self):
+        """Test get_model_token_limit with planner provider and model."""
+        config = {
+            "provider": "openai",
+            "model": "gpt-4",
+            "planner_provider": "deepseek",
+            "planner_model": "dsm-1",
+        }
+        
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo, \
+             patch("litellm.get_model_info") as mock_get_info:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            mock_get_info.return_value = {"max_input_tokens": 120000}
+            token_limit = get_model_token_limit(config, "planner")
+            self.assertEqual(token_limit, 120000)
+            # Verify get_model_info was called with the planner model
+            mock_get_info.assert_called_with("deepseek/dsm-1")
+
+    @patch("ra_aid.anthropic_token_limiter.get_config_repository")
+    @patch("litellm.get_model_info")
+    def test_get_model_token_limit_fallback(self, mock_get_model_info, mock_get_config_repo):
+        # Setup mocks
+        mock_config = {"provider": "anthropic", "model": "claude-2"}
+        mock_get_config_repo.return_value.get_all.return_value = mock_config
+        
+        # Make litellm's get_model_info raise an exception to test fallback
+        mock_get_model_info.side_effect = Exception("Model not found")
+        
+        # Test getting token limit from models_params fallback
+        with patch("ra_aid.anthropic_token_limiter.models_params", {
+            "anthropic": {
+                "claude2": {"token_limit": 100000}
+            }
+        }):
+            result = get_model_token_limit(mock_config)
+            self.assertEqual(result, 100000)
+
+    @patch("ra_aid.anthropic_token_limiter.get_config_repository")
+    @patch("litellm.get_model_info")
+    def test_get_model_token_limit_for_different_agent_types(self, mock_get_model_info, mock_get_config_repo):
+        from ra_aid.config import DEFAULT_MODEL
+        
+        # Setup mocks for different agent types
+        mock_config = {
+            "provider": "anthropic", 
+            "model": DEFAULT_MODEL,
+            "research_provider": "openai",
+            "research_model": "gpt-4",
+            "planner_provider": "anthropic",
+            "planner_model": "claude-3-sonnet-20240229"
+        }
+        mock_get_config_repo.return_value.get_all.return_value = mock_config
+        
+        # Mock different returns for different models
+        def model_info_side_effect(model_name):
+            if DEFAULT_MODEL in model_name or "claude-3-7-sonnet" in model_name:
+                return {"max_input_tokens": 200000}
+            elif "gpt-4" in model_name:
+                return {"max_input_tokens": 8192}
+            elif "claude-3-sonnet" in model_name:
+                return {"max_input_tokens": 100000}
+            else:
+                raise Exception(f"Unknown model: {model_name}")
+                
+        mock_get_model_info.side_effect = model_info_side_effect
+        
+        # Test default agent type
+        result = get_model_token_limit(mock_config, "default")
+        self.assertEqual(result, 200000)
+        
+        # Test research agent type
+        result = get_model_token_limit(mock_config, "research")
+        self.assertEqual(result, 8192)
+        
+        # Test planner agent type
+        result = get_model_token_limit(mock_config, "planner")
+        self.assertEqual(result, 100000)
+        
+    def test_get_model_token_limit_anthropic(self):
+        """Test get_model_token_limit with Anthropic model."""
+        config = {"provider": "anthropic", "model": "claude2"}
+        
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            token_limit = get_model_token_limit(config, "default")
+            self.assertEqual(token_limit, models_params["anthropic"]["claude2"]["token_limit"])
+
+    def test_get_model_token_limit_openai(self):
+        """Test get_model_token_limit with OpenAI model."""
+        config = {"provider": "openai", "model": "gpt-4"}
+        
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            token_limit = get_model_token_limit(config, "default")
+            self.assertEqual(token_limit, models_params["openai"]["gpt-4"]["token_limit"])
+
+    def test_get_model_token_limit_unknown(self):
+        """Test get_model_token_limit with unknown provider/model."""
+        config = {"provider": "unknown", "model": "unknown-model"}
+        
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            token_limit = get_model_token_limit(config, "default")
+            self.assertIsNone(token_limit)
+
+    def test_get_model_token_limit_missing_config(self):
+        """Test get_model_token_limit with missing configuration."""
+        config = {}
+        
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            token_limit = get_model_token_limit(config, "default")
+            self.assertIsNone(token_limit)
+
+    def test_get_model_token_limit_litellm_success(self):
+        """Test get_model_token_limit successfully getting limit from litellm."""
+        config = {"provider": "anthropic", "model": "claude-2"}
+
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo, \
+             patch("litellm.get_model_info") as mock_get_info:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            mock_get_info.return_value = {"max_input_tokens": 100000}
+            token_limit = get_model_token_limit(config, "default")
+            self.assertEqual(token_limit, 100000)
+            mock_get_info.assert_called_with("anthropic/claude-2")
+
+    def test_get_model_token_limit_litellm_not_found(self):
+        """Test fallback to models_tokens when litellm raises NotFoundError."""
+        config = {"provider": "anthropic", "model": "claude-2"}
+
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo, \
+             patch("litellm.get_model_info") as mock_get_info:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            mock_get_info.side_effect = litellm.exceptions.NotFoundError(
+                message="Model not found", model="claude-2", llm_provider="anthropic"
+            )
+            token_limit = get_model_token_limit(config, "default")
+            self.assertEqual(token_limit, models_params["anthropic"]["claude2"]["token_limit"])
+
+    def test_get_model_token_limit_litellm_error(self):
+        """Test fallback to models_tokens when litellm raises other exceptions."""
+        config = {"provider": "anthropic", "model": "claude-2"}
+
+        with patch("ra_aid.anthropic_token_limiter.get_config_repository") as mock_get_config_repo, \
+             patch("litellm.get_model_info") as mock_get_info:
+            mock_get_config_repo.return_value.get_all.return_value = config
+            mock_get_info.side_effect = Exception("Unknown error")
+            token_limit = get_model_token_limit(config, "default")
+            self.assertEqual(token_limit, models_params["anthropic"]["claude2"]["token_limit"])
+
+    def test_get_model_token_limit_unexpected_error(self):
+        """Test returning None when unexpected errors occur."""
+        config = None  # This will cause an attribute error when accessed
+
+        token_limit = get_model_token_limit(config, "default")
+        self.assertIsNone(token_limit)
+        
+    def test_has_tool_use(self):
+        """Test the has_tool_use function."""
+        # Test with regular AI message
+        self.assertFalse(has_tool_use(self.ai_message))
+        
+        # Test with AI message containing tool_use in string content
+        ai_with_tool_str = AIMessage(content="I'll use a tool_use to help you")
+        self.assertTrue(has_tool_use(ai_with_tool_str))
+        
+        # Test with AI message containing tool_use in structured content
+        ai_with_tool_dict = AIMessage(content=[
+            {"type": "text", "text": "I'll use a tool to help you"},
+            {"type": "tool_use", "tool_use": {"name": "calculator", "input": {"expression": "2+2"}}}
+        ])
+        self.assertTrue(has_tool_use(ai_with_tool_dict))
+        
+        # Test with AI message containing tool_calls in additional_kwargs
+        self.assertTrue(has_tool_use(self.ai_with_tool_use))
+        
+        # Test with non-AI message
+        self.assertFalse(has_tool_use(self.human_message))
+        
+    def test_is_tool_pair(self):
+        """Test the is_tool_pair function."""
+        # Test with valid tool pair
+        self.assertTrue(is_tool_pair(self.ai_with_tool_use, self.tool_message))
+        
+        # Test with non-tool pair (wrong order)
+        self.assertFalse(is_tool_pair(self.tool_message, self.ai_with_tool_use))
+        
+        # Test with non-tool pair (wrong types)
+        self.assertFalse(is_tool_pair(self.ai_message, self.human_message))
+        
+        # Test with non-tool pair (AI message without tool use)
+        self.assertFalse(is_tool_pair(self.ai_message, self.tool_message))
+        
+    @patch("ra_aid.anthropic_message_utils.has_tool_use")
+    def test_anthropic_trim_messages_with_tool_use(self, mock_has_tool_use):
+        """Test anthropic_trim_messages with a sequence of messages including tool use."""
+        from ra_aid.anthropic_message_utils import anthropic_trim_messages
+        
+        # Setup mock for has_tool_use to return True for AI messages at even indices
+        def side_effect(msg):
+            if isinstance(msg, AIMessage) and hasattr(msg, 'test_index'):
+                return msg.test_index % 2 == 0  # Even indices have tool use
+            return False
+            
+        mock_has_tool_use.side_effect = side_effect
+        
+        # Create a sequence of alternating human and AI messages with tool use
+        messages = []
+        
+        # Start with system message
+        system_msg = SystemMessage(content="You are a helpful assistant.")
+        messages.append(system_msg)
+        
+        # Add alternating human and AI messages with tool use
+        for i in range(8):
+            if i % 2 == 0:
+                # Human message
+                msg = HumanMessage(content=f"Human message {i}")
+                messages.append(msg)
+            else:
+                # AI message, every other one has tool use
+                ai_msg = AIMessage(content=f"AI message {i}")
+                # Add a test_index attribute to track position
+                ai_msg.test_index = i
+                messages.append(ai_msg)
+                
+                # If this AI message has tool use (even index), add a tool message after it
+                if i % 4 == 1:  # 1, 5, etc.
+                    tool_msg = ToolMessage(
+                        content=f"Tool result {i}",
+                        tool_call_id=f"tool_call_{i}",
+                        name="test_tool"
+                    )
+                    messages.append(tool_msg)
+        
+        # Define a token counter that returns a fixed value per message
+        def token_counter(msgs):
+            return len(msgs) * 1000
+            
+        # Test with a token limit that will require trimming
+        result = anthropic_trim_messages(
+            messages,
+            token_counter=token_counter,
+            max_tokens=5000,  # This will allow 5 messages
+            strategy="last",
+            allow_partial=False,
+            include_system=True,
+            num_messages_to_keep=2  # Keep system and first human message
+        )
+        
+        # We should have kept the first 2 messages (system + human)
+        self.assertEqual(len(result), 5)  # 2 kept + 3 more that fit in token limit
+        self.assertEqual(result[0], system_msg)
+        
+        # Verify that we don't have any AI messages with tool use that aren't followed by a tool message
+        for i in range(len(result) - 1):
+            if isinstance(result[i], AIMessage) and mock_has_tool_use(result[i]):
+                self.assertTrue(isinstance(result[i+1], ToolMessage), 
+                               f"AI message with tool use at index {i} not followed by ToolMessage")
+
+
+if __name__ == "__main__":
+    unittest.main()