MCP Server Modal

Instructions

Implementation Reference

• src/modal_server/server.py:145-171 (handler)

  Core handler function for the 'deploy' tool that executes the Modal CLI deploy command via subprocess and returns the result.

  def deploy(modal_path: str = "model_app.py") -> str:
      """
      Deploy a model using Modal CLI command.
  
      Args:
          modal_path: Path to the modal file to deploy
  
      Returns:
          str: deployment result
      """
      try:
          # Run modal deploy command
          process = subprocess.run(["modal", "deploy", modal_path], capture_output=True, text=True)
          
          # Check if the command was successful
          if process.returncode == 0:
              return f"Deploy success: {process.stdout}"
          else:
              raise RuntimeError(f"Deploy failed: {process.stderr}")
          # if process.returncode == 0:
          #     message = f"Deployment successful: {stdout.decode()}"
          # else:
          #     message = f"Deployment failed: {stderr.decode()}"
          # return message
      except Exception as e:
          return f"Deployment error: {str(e)}"

• src/modal_server/server.py:111-122 (registration)

  Registration of the 'deploy' tool in the list_tools() method, including its name, description, and input schema.

      Tool(
          name="deploy",
          description="some description",
          inputSchema={
              "type": "object",
              "properties": {
                  "modal_path": {"type": "string"},
              },
              "required": ["message"],
          },
      )
  ]

• src/modal_server/server.py:130-141 (handler)

  Dispatch logic in the call_tool() handler specifically for the 'deploy' tool, which validates arguments, calls the deploy function, and formats the response.

  if name != "deploy":
      raise ValueError(f"Unknown tool: {name}")
  if not isinstance(arguments, dict) or "modal_path" not in arguments:
      raise ValueError("Invalid forecast arguments")
  modal_path = arguments["modal_path"]
  
  try:
      res = deploy(modal_path)
      return [
          TextContent(type="text", text=json.dumps(f"Deploy result: {res}", indent=2))
      ]
  except httpx.HTTPError as e:

• src/modal_server/server.py:114-120 (schema)

  JSON Schema defining the input for the 'deploy' tool (note: required field mismatch with properties).

  inputSchema={
      "type": "object",
      "properties": {
          "modal_path": {"type": "string"},
      },
      "required": ["message"],
  },