simple_mcp_patch.py

"""
Simple and targeted patch for MCP client to handle the specific JSON-RPC validation error.
This focuses only on the call_tool method which is where the error occurs.
"""

import logging
from typing import Any

# Set up logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

def patch_mcp_call_tool_simple():
    """
    Simple patch for the call_tool method to handle JSON-RPC validation errors.
    """
    try:
        from mcp.client.session import ClientSession
        from mcp.types import CallToolResult, TextContent
        
        # Store the original call_tool method
        original_call_tool = ClientSession.call_tool
        
        async def patched_call_tool(self, name: str, arguments: dict[str, Any] | None = None):
            """
            Patched call_tool that handles JSON-RPC validation errors gracefully.
            """
            try:
                return await original_call_tool(self, name, arguments)
            except Exception as e:
                error_msg = str(e)
                logger.error(f"MCP call_tool error for '{name}': {error_msg}")
                
                # Handle the specific JSON-RPC validation error
                if "validation errors for JSONRPCMessage" in error_msg:
                    error_content = TextContent(
                        type="text",
                        text=f"Tool '{name}' returned an invalid response from the server. This tool may not be properly configured or available."
                    )
                elif "Invalid tool call and request method" in error_msg:
                    error_content = TextContent(
                        type="text", 
                        text=f"Tool '{name}' is not available or the parameters are incorrect."
                    )
                elif "Field required" in error_msg and "missing" in error_msg:
                    error_content = TextContent(
                        type="text",
                        text=f"Server configuration error for tool '{name}'. The server response is malformed."
                    )
                else:
                    error_content = TextContent(
                        type="text",
                        text=f"Tool '{name}' encountered an error: {error_msg}"
                    )
                
                return CallToolResult(
                    content=[error_content],
                    isError=True
                )
        
        # Apply the patch
        ClientSession.call_tool = patched_call_tool
        logger.info("Successfully patched MCP ClientSession.call_tool")
        return True
        
    except ImportError as e:
        logger.error(f"Could not import MCP ClientSession: {e}")
        return False
    except Exception as e:
        logger.error(f"Failed to patch MCP ClientSession.call_tool: {e}")
        return False

if __name__ == "__main__":
    success = patch_mcp_call_tool_simple()
    if success:
        print("✅ Simple MCP call_tool patching completed")
    else:
        print("❌ Simple MCP call_tool patching failed")