MCP Server for Apache Airflow

Instructions

Implementation Reference

• src/airflow/dag.py:40-77 (handler)

  Handler function that implements the core logic of the 'fetch_dags' tool. Fetches DAGs from Airflow API with optional parameters, enhances with UI URLs, and returns as MCP TextContent.

  async def get_dags(
      limit: Optional[int] = None,
      offset: Optional[int] = None,
      order_by: Optional[str] = None,
      tags: Optional[List[str]] = None,
      only_active: Optional[bool] = None,
      paused: Optional[bool] = None,
      dag_id_pattern: Optional[str] = None,
  ) -> List[Union[types.TextContent, types.ImageContent, types.EmbeddedResource]]:
      # Build parameters dictionary
      kwargs: Dict[str, Any] = {}
      if limit is not None:
          kwargs["limit"] = limit
      if offset is not None:
          kwargs["offset"] = offset
      if order_by is not None:
          kwargs["order_by"] = order_by
      if tags is not None:
          kwargs["tags"] = tags
      if only_active is not None:
          kwargs["only_active"] = only_active
      if paused is not None:
          kwargs["paused"] = paused
      if dag_id_pattern is not None:
          kwargs["dag_id_pattern"] = dag_id_pattern
  
      # Use the client to fetch DAGs
      response = dag_api.get_dags(**kwargs)
  
      # Convert response to dictionary for easier manipulation
      response_dict = response.to_dict()
  
      # Add UI links to each DAG
      for dag in response_dict.get("dags", []):
          dag["ui_url"] = get_dag_url(dag["dag_id"])
  
      return [types.TextContent(type="text", text=str(response_dict))]

• src/airflow/dag.py:15-33 (registration)

  Defines the list of tool functions for DAG API, including the registration tuple for 'fetch_dags' which associates the get_dags handler with the tool name, description, and read-only flag.

  def get_all_functions() -> list[tuple[Callable, str, str, bool]]:
      """Return list of (function, name, description, is_read_only) tuples for registration."""
      return [
          (get_dags, "fetch_dags", "Fetch all DAGs", True),
          (get_dag, "get_dag", "Get a DAG by ID", True),
          (get_dag_details, "get_dag_details", "Get a simplified representation of DAG", True),
          (get_dag_source, "get_dag_source", "Get a source code", True),
          (pause_dag, "pause_dag", "Pause a DAG by ID", False),
          (unpause_dag, "unpause_dag", "Unpause a DAG by ID", False),
          (get_dag_tasks, "get_dag_tasks", "Get tasks for DAG", True),
          (get_task, "get_task", "Get a task by ID", True),
          (get_tasks, "get_tasks", "Get tasks for DAG", True),
          (patch_dag, "patch_dag", "Update a DAG", False),
          (patch_dags, "patch_dags", "Update multiple DAGs", False),
          (delete_dag, "delete_dag", "Delete a DAG", False),
          (clear_task_instances, "clear_task_instances", "Clear a set of task instances", False),
          (set_task_instances_state, "set_task_instances_state", "Set a state of task instances", False),
          (reparse_dag_file, "reparse_dag_file", "Request re-parsing of a DAG file", False),
      ]

• src/main.py:92-97 (registration)

  The code in main.py that iterates over the functions from get_dag_functions() (among others) and registers each tool with the MCP app using app.add_tool.

  if read_only:
      functions = filter_functions_for_read_only(functions)
  
  for func, name, description, *_ in functions:
      app.add_tool(Tool.from_function(func, name=name, description=description))

• src/airflow/dag.py:36-38 (helper)

  Helper function used by get_dags to generate UI URLs for each DAG.

  def get_dag_url(dag_id: str) -> str:
      return f"{AIRFLOW_HOST}/dags/{dag_id}/grid"

• src/main.py:8-9 (registration)

  Import of get_all_functions from dag.py, aliased as get_dag_functions, which is used to load the tool registrations.

  from src.airflow.dag import get_all_functions as get_dag_functions
  from src.airflow.dagrun import get_all_functions as get_dagrun_functions