Modal MCP Server

Instructions

Implementation Reference

• src/modal_mcp/server.py:268-311 (handler)

  The main handler function for the 'get_modal_volume_file' tool. It constructs a 'modal volume get' CLI command based on input parameters and executes it using run_modal_command helper. Returns a standardized response with success status, message, stdout, stderr.
  @mcp.tool() async def get_modal_volume_file(volume_name: str, remote_path: str, local_destination: str = ".", force: bool = False) -> dict[str, Any]: """ Download files from a Modal volume. Args: volume_name: Name of the Modal volume to download from. remote_path: Path to the file or directory in the volume to download. local_destination: Local path to save the downloaded file(s). Defaults to current directory. Use "-" to write file contents to stdout. force: If True, overwrite existing files. Defaults to False. Returns: A dictionary containing the result of the download operation. Raises: Exception: If the download operation fails for any reason. """ try: command = ["modal", "volume", "get"] if force: command.append("--force") command.extend([volume_name, remote_path, local_destination]) result = run_modal_command(command) response = { "success": result["success"], "command": result["command"] } if not result["success"]: response["error"] = f"Failed to download {remote_path}: {result.get('error', 'Unknown error')}" else: response["message"] = f"Successfully downloaded {remote_path} from volume {volume_name}" if result.get("stdout"): response["stdout"] = result["stdout"] if result.get("stderr"): response["stderr"] = result["stderr"] return response except Exception as e: logger.error(f"Failed to download from Modal volume: {e}") raise
• src/modal_mcp/server.py:268-268 (registration)

  The @mcp.tool() decorator registers the get_modal_volume_file function as an MCP tool.
  @mcp.tool()
• src/modal_mcp/server.py:270-284 (schema)

  Docstring defining the input parameters, return type, and behavior, serving as the tool schema.
  """ Download files from a Modal volume. Args: volume_name: Name of the Modal volume to download from. remote_path: Path to the file or directory in the volume to download. local_destination: Local path to save the downloaded file(s). Defaults to current directory. Use "-" to write file contents to stdout. force: If True, overwrite existing files. Defaults to False. Returns: A dictionary containing the result of the download operation. Raises: Exception: If the download operation fails for any reason.
• src/modal_mcp/server.py:15-41 (helper)

  Helper function used by get_modal_volume_file to execute the modal CLI command via subprocess.
  def run_modal_command(command: list[str], uv_directory: str = None) -> dict[str, Any]: """Run a Modal CLI command and return the result""" try: # uv_directory is necessary for modal deploy, since deploying the app requires the app to use the uv venv command = (["uv", "run", f"--directory={uv_directory}"] if uv_directory else []) + command logger.info(f"Running command: {' '.join(command)}") result = subprocess.run( command, capture_output=True, text=True, check=True ) return { "success": True, "stdout": result.stdout, "stderr": result.stderr, "command": ' '.join(command) } except subprocess.CalledProcessError as e: return { "success": False, "error": str(e), "stdout": e.stdout, "stderr": e.stderr, "command": ' '.join(command) }