Tool Adapter

# Tool Adapter

Wrap legacy APIs as agent-friendly tools.

## Category
Compositional

## Context
Integrating existing APIs that weren't designed for agents.

## Problem
Legacy APIs have poor descriptions, complex auth, or unfriendly responses.

## Solution
Build adapters that:
- **Wrap**: Hide legacy complexity
- **Document**: Add LLM-friendly descriptions
- **Transform**: Shape responses appropriately
- **Handle auth**: Manage credentials

## Example (Python)
```python
# Legacy API: Poor documentation, nested response
class LegacyUserAPI:
    def GetUserByID(self, uid, include_all=False):
        # Returns deeply nested, poorly documented response
        pass

# Adapter: Agent-friendly wrapper
@tool
def get_user(user_id: str) -> UserProfile:
    """Get user profile by ID.
    
    Returns a clean UserProfile with name, email, role.
    Call search_users() first if you only have a name.
    """
    legacy = LegacyUserAPI()
    raw = legacy.GetUserByID(user_id, include_all=True)
    return UserProfile(
        id=raw["data"]["user"]["uid"],
        name=raw["data"]["user"]["profile"]["displayName"],
        email=raw["data"]["user"]["contact"]["primaryEmail"],
        role=raw["data"]["user"]["access"]["role"]
    )
```

## Considerations
- Focus on the 80% use case, not all features
- Add comprehensive documentation
- Shape responses for token efficiency

## Related Patterns
- response-shaper
- tool-description
- tool-gateway

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Source: https://arcade.dev/patterns/tool-adapter