atlas/home-voice-agent/mcp-adapter/adapter.py

"""
MCP-LLM Adapter - Converts between LLM function calls and MCP tool calls.
"""

import logging
import requests
from typing import Any, Dict, List, Optional
import json

logger = logging.getLogger(__name__)


class MCPAdapter:
    """
    Adapter that converts LLM function calls to MCP tool calls and back.
    
    Supports OpenAI-compatible function calling format.
    """
    
    def __init__(self, mcp_server_url: str = "http://localhost:8000/mcp"):
        """
        Initialize MCP adapter.
        
        Args:
            mcp_server_url: URL of the MCP server endpoint
        """
        self.mcp_server_url = mcp_server_url
        self._tools_cache: Optional[List[Dict[str, Any]]] = None
        self._request_id = 0
    
    def _next_request_id(self) -> int:
        """Get next request ID for JSON-RPC."""
        self._request_id += 1
        return self._request_id
    
    def _make_mcp_request(self, method: str, params: Optional[Dict[str, Any]] = None) -> Dict[str, Any]:
        """
        Make a JSON-RPC request to MCP server.
        
        Args:
            method: JSON-RPC method name
            params: Method parameters
            
        Returns:
            JSON-RPC response
        """
        request = {
            "jsonrpc": "2.0",
            "method": method,
            "id": self._next_request_id()
        }
        
        if params:
            request["params"] = params
        
        try:
            response = requests.post(
                self.mcp_server_url,
                json=request,
                headers={"Content-Type": "application/json"},
                timeout=30
            )
            response.raise_for_status()
            return response.json()
        except requests.exceptions.RequestException as e:
            logger.error(f"MCP request failed: {e}")
            raise
    
    def discover_tools(self, force_refresh: bool = False) -> List[Dict[str, Any]]:
        """
        Discover available tools from MCP server.
        
        Args:
            force_refresh: Force refresh of cached tools
            
        Returns:
            List of tools in OpenAI function format
        """
        if self._tools_cache is None or force_refresh:
            logger.info("Discovering tools from MCP server...")
            response = self._make_mcp_request("tools/list")
            
            # Check for actual errors (error field exists and is not None)
            if "error" in response and response["error"] is not None:
                error = response["error"]
                error_msg = f"MCP error: {error.get('message', 'Unknown error')}"
                logger.error(error_msg)
                raise Exception(error_msg)
            
            mcp_tools = response.get("result", {}).get("tools", [])
            
            # Convert MCP tool format to OpenAI function format
            self._tools_cache = []
            for tool in mcp_tools:
                openai_tool = {
                    "type": "function",
                    "function": {
                        "name": tool["name"],
                        "description": tool["description"],
                        "parameters": tool.get("inputSchema", {})
                    }
                }
                self._tools_cache.append(openai_tool)
            
            logger.info(f"Discovered {len(self._tools_cache)} tools")
        
        return self._tools_cache
    
    def call_tool(self, function_call: Dict[str, Any]) -> str:
        """
        Call a tool via MCP server.
        
        Args:
            function_call: LLM function call in OpenAI format
                {
                    "name": "tool_name",
                    "arguments": {...}
                }
        
        Returns:
            Tool result as string (for LLM to process)
        """
        tool_name = function_call.get("name")
        arguments = function_call.get("arguments", {})
        
        if not tool_name:
            raise ValueError("Function call missing 'name' field")
        
        logger.info(f"Calling tool: {tool_name} with arguments: {arguments}")
        
        # Make MCP call
        response = self._make_mcp_request(
            "tools/call",
            params={
                "name": tool_name,
                "arguments": arguments
            }
        )
        
        # Handle errors (check if error exists and is not None)
        if "error" in response and response["error"] is not None:
            error = response["error"]
            error_msg = f"Tool '{tool_name}' failed: {error.get('message', 'Unknown error')}"
            logger.error(error_msg)
            raise Exception(error_msg)
        
        # Extract result content
        result = response.get("result", {})
        content = result.get("content", [])
        
        # Convert MCP content to string for LLM
        if not content:
            return f"Tool '{tool_name}' returned no content"
        
        # Combine all text content
        text_parts = []
        for item in content:
            if item.get("type") == "text":
                text_parts.append(item.get("text", ""))
        
        result_text = "\n".join(text_parts) if text_parts else f"Tool '{tool_name}' executed successfully"
        
        logger.info(f"Tool '{tool_name}' returned: {result_text[:100]}...")
        return result_text
    
    def get_tools_for_llm(self) -> List[Dict[str, Any]]:
        """
        Get tools in OpenAI function format for LLM.
        
        Returns:
            List of tools in OpenAI format
        """
        tools = self.discover_tools()
        return [tool["function"] for tool in tools]
    
    def health_check(self) -> bool:
        """
        Check if MCP server is healthy.
        
        Returns:
            True if server is healthy, False otherwise
        """
        try:
            response = requests.get(
                self.mcp_server_url.replace("/mcp", "/health"),
                timeout=5
            )
            return response.status_code == 200
        except Exception as e:
            logger.error(f"Health check failed: {e}")
            return False