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.. _howto/connection:mcp:

MCP Server Connection
=====================

The MCP connection type configures access to
`MCP (Model Context Protocol) <https://modelcontextprotocol.io/>`__ servers.
Three transport types are supported: Streamable HTTP, SSE, and stdio.

Default Connection IDs
----------------------

The ``MCPHook`` uses ``mcp_default`` by default.

Configuring the Connection
--------------------------

Transport (Extra field)
    The transport type: ``http`` (default), ``sse``, or ``stdio``.

    - ``http``: Streamable HTTP — the recommended transport for remote servers.
    - ``sse``: Server-Sent Events — deprecated in favor of Streamable HTTP.
    - ``stdio``: Run the MCP server as a subprocess communicating over stdin/stdout.

Host
    The server URL. Required for ``http`` and ``sse`` transports.

    Examples: ``http://localhost:3001/mcp``, ``https://mcp.example.com/v1``

Auth Token (Password field)
    Optional authentication token for the MCP server. Sent as a static
    ``Authorization: Bearer <token>`` header on HTTP/SSE transports. For
    short-lived or minted tokens, use a ``token_provider`` instead (see below).

Command (Extra field)
    The command to run for ``stdio`` transport. Required when transport is ``stdio``.

    Examples: ``uvx``, ``python``, ``node``

Arguments (Extra field)
    JSON array of arguments for the stdio command.

    Examples: ``["mcp-run-python"]``, ``["-m", "my_mcp_server"]``

Examples
--------

**HTTP transport (remote MCP server)**

.. code-block:: json

    {
        "conn_type": "mcp",
        "host": "http://localhost:3001/mcp"
    }

**SSE transport**

.. code-block:: json

    {
        "conn_type": "mcp",
        "host": "http://localhost:3001/sse",
        "extra": "{\"transport\": \"sse\"}"
    }

**Stdio transport (subprocess)**

.. code-block:: json

    {
        "conn_type": "mcp",
        "extra": "{\"transport\": \"stdio\", \"command\": \"uvx\", \"args\": [\"mcp-run-python\"]}"
    }

**Stdio with custom timeout**

.. code-block:: json

    {
        "conn_type": "mcp",
        "extra": "{\"transport\": \"stdio\", \"command\": \"python\", \"args\": [\"-m\", \"my_server\"], \"timeout\": 30}"
    }

Short-lived or minted tokens
----------------------------

Some MCP endpoints require a freshly minted, short-lived token rather than a
static one. For example, `Snowflake managed MCP servers
<https://docs.snowflake.com/en/user-guide/snowflake-cortex/cortex-agents-mcp>`__
are best authenticated with a `key-pair JWT
<https://docs.snowflake.com/en/user-guide/key-pair-auth>`__: the private key never
leaves your environment and the signed JWT expires after about an hour, so it
cannot be stored as a static connection ``password``. The same applies to OAuth /
refresh tokens, Workload Identity Federation, and GitHub App installation tokens.

For these, pass a ``token_provider`` callable to ``MCPHook`` or ``MCPToolset``
instead of a static token. It is called each time the connection is established
and its return value is used as the bearer token, so a fresh token is minted (and
registered with secret masking so it does not leak into task logs):

.. code-block:: python

    from airflow.providers.common.ai.toolsets.mcp import MCPToolset


    def mint_snowflake_jwt() -> str:
        # Sign a short-lived JWT from the Snowflake connection's key-pair.
        ...


    toolset = MCPToolset(
        mcp_conn_id="snowflake_managed_mcp",
        token_provider=mint_snowflake_jwt,
    )

``token_provider`` is resolved in DAG code (it is a Python callable, not a stored
connection field), so the signing key stays in your environment and is never baked
into the serialized DAG.
