diff --git a/README.md b/README.md
index 433b577..18472b6 100644
--- a/README.md
+++ b/README.md
@@ -104,20 +104,26 @@ pip install aider-chat
 2. API keys for the required AI services:
 
 ```bash
-# Default: Set up Anthropic API key (default provider)
+# Set up API keys based on your preferred provider:
+
+# For Anthropic Claude models (recommended)
 export ANTHROPIC_API_KEY=your_api_key_here
 
-# Required for expert tool and OpenAI provider
+# For OpenAI models
 export OPENAI_API_KEY=your_api_key_here
 
-# Required for OpenRouter provider
+# For OpenRouter provider (optional)
 export OPENROUTER_API_KEY=your_api_key_here
 
-# For OpenAI-compatible providers
-export OPENAI_API_KEY=your_api_key_here
+# For OpenAI-compatible providers (optional)
 export OPENAI_API_BASE=your_api_base_url
 ```
 
+Note: The programmer tool (aider) will automatically select its model based on your available API keys:
+- If ANTHROPIC_API_KEY is set, it will use Claude models
+- If only OPENAI_API_KEY is set, it will use OpenAI models
+- You can set multiple API keys to enable different features
+
 You can get your API keys from:
 - Anthropic API key: https://console.anthropic.com/
 - OpenAI API key: https://platform.openai.com/api-keys
@@ -147,6 +153,8 @@ ra-aid -m "Explain the authentication flow" --research-only
 
 RA.Aid supports multiple AI providers and models. The default model is Anthropic's Claude 3 Sonnet (`claude-3-5-sonnet-20241022`).
 
+The programmer tool (aider) automatically selects its model based on your available API keys. It will use Claude models if ANTHROPIC_API_KEY is set, or fall back to OpenAI models if only OPENAI_API_KEY is available.
+
 #### Environment Variables
 
 RA.Aid supports multiple providers through environment variables:
@@ -172,7 +180,7 @@ export OPENROUTER_API_KEY=your_api_key_here
 export OPENAI_API_BASE=your_api_base_url
 ```
 
-Note: The expert tool always uses OpenAI's `o1-preview` model and requires `OPENAI_API_KEY` to be set, even if you're using a different provider for the main application. Additionally, the programmer tool (aider) is currently hardcoded to use Anthropic Claude - this is something we plan to fix in a future update.
+Note: The expert tool always uses OpenAI's `o1-preview` model and requires `OPENAI_API_KEY` to be set, even if you're using a different provider for the main application.
 
 #### Examples
 
diff --git a/ra_aid/tools/shell.py b/ra_aid/tools/shell.py
index 9324fe4..db150d0 100644
--- a/ra_aid/tools/shell.py
+++ b/ra_aid/tools/shell.py
@@ -14,11 +14,6 @@ console = Console()
 def run_shell_command(command: str) -> Dict[str, Union[str, int, bool]]:
     """Execute a shell command and return its output.
 
-    Assume these are available:
-    - rg
-    - tree
-    - standard linux utilities
-
     Important notes:
     1. Try to constrain/limit the output. Output processing is expensive, and infinite/looping output will cause us to fail.
     2. When using commands like 'find', 'grep', or similar recursive search tools, always exclude common