MCP Pyrefly Autotype Server

Instructions

Implementation Reference

• src/mcp_pyrefly_autotype/server.py:495-516 (handler)

  Handler implementation in handle_call_tool for 'type_check_file': validates file_path, calls run_pyrefly_check helper, formats and returns type check results as text content.

  elif name == "type_check_file":
      file_path = arguments.get("file_path")
      
      if not file_path:
          raise ValueError("Missing file_path argument")
      
      if not os.path.exists(file_path):
          raise ValueError(f"File not found: {file_path}")
      
      result = await run_pyrefly_check(file_path)
      
      if result["success"]:
          return [types.TextContent(
              type="text", 
              text=f"Type checking passed for {file_path}\n\nOutput:\n{result['output']}"
          )]
      else:
          return [types.TextContent(
              type="text", 
              text=f"Type checking found issues in {file_path}\n\nErrors:\n{result['output']}\n{result.get('errors', '')}"
          )]

• src/mcp_pyrefly_autotype/server.py:385-398 (registration)

  Registration of the 'type_check_file' tool in the list_tools() handler, including its description and input schema requiring 'file_path'.

  types.Tool(
      name="type_check_file",
      description="Run type checking on a Python file using Pyrefly",
      inputSchema={
          "type": "object",
          "properties": {
              "file_path": {
                  "type": "string",
                  "description": "Path to the Python file to type check"
              }
          },
          "required": ["file_path"],
      },
  ),

• src/mcp_pyrefly_autotype/server.py:388-397 (schema)

  Input schema definition for the 'type_check_file' tool: object with required 'file_path' string property.

  inputSchema={
      "type": "object",
      "properties": {
          "file_path": {
              "type": "string",
              "description": "Path to the Python file to type check"
          }
      },
      "required": ["file_path"],
  },

• src/mcp_pyrefly_autotype/server.py:136-161 (helper)

  Helper function that executes the 'pyrefly check' subprocess command on a given file_path and returns a structured result dict with success status, output, and errors.

  async def run_pyrefly_check(file_path: str) -> Dict[str, Any]:
      """Run pyrefly type checking on a file."""
      try:
          result = subprocess.run(
              ["uv", "run", "pyrefly", "check", file_path],
              capture_output=True,
              text=True,
              timeout=30
          )
          
          return {
              "success": result.returncode == 0,
              "output": result.stdout,
              "errors": result.stderr,
              "returncode": result.returncode
          }
      except subprocess.TimeoutExpired:
          return {
              "success": False,
              "error": "Pyrefly check execution timed out"
          }
      except Exception as e:
          return {
              "success": False,
              "error": str(e)
          }