MCP server connection¶

The MCP connection type configures access to MCP (Model Context Protocol) 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, pass a token_provider to MCPToolset instead (see MCP servers: MCPToolset).

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"]

Environment (Extra field)

JSON object of environment variables for the stdio subprocess. Ignored for http/sse. For a secret that lives in a different connection or is minted fresh per call, pass an env_provider to MCPToolset instead of storing it here (see MCP servers: MCPToolset).

Examples: {"MY_SERVER_MODE": "readonly"}

Timeout (Extra field)

Connection init timeout in seconds for the stdio transport. Ignored for http/sse. Default: 10.

Examples: 30

Examples¶

HTTP transport (remote MCP server)

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

SSE transport

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

Stdio transport (subprocess)

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

Stdio with custom timeout

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

Stdio with subprocess environment variables

{
    "conn_type": "mcp",
    "extra": "{\"transport\": \"stdio\", \"command\": \"my-mcp-server\", \"args\": [], \"env\": {\"SERVER_MODE\": \"readonly\"}}"
}