[MCP] Hope to be able to customize HTTP Header.

[wirs1214-alt]

Is your feature request related to a problem? Please describe.
This scenario occurred because the MCP Server I needed to connect to used an unconventional Authorization header, which prevented me from successfully authenticating. Moreover, the tool currently does not support providing custom headers.

Describe the solution you'd like
Hope to be able to customize HTTP Header.

[vblagoje]

@wirs1214-alt can you share more about your use case so we can have the customizable header in place for MCP? We are planning to accommodate the OAuth 2.1 MCP workflows in pipelines and agents as recommended by MCP spec but the openness to supporting these unusual cases of MCP auth out there, if requested by the community, is certainly ok as well. Let us know

[wirs1214-alt]

The scenario I encountered is that the developers at the MCP Server backend are using the form of "X-xxx" to receive tokens and verify identities on their own. This seems to be inconsistent with the standard specifications of MCP, but at the same time, I also hope that the haystack mcp tool can support custom headers. This greatly increases the flexibility of the tool and can solve some unexpected situations. @vblagoje

[vblagoje]

So all you are asking for @wirs1214-alt is an option to specify your headers similar to these examples:

    # API key authentication
    server_info = StreamableHttpServerInfo(
        url="https://my-mcp-server.com",
        headers={"X-API-Key": Secret.from_env_var("API_KEY")},
    )
    # Multiple headers
    server_info = StreamableHttpServerInfo(
        url="https://my-mcp-server.com",
        headers={
            "X-API-Key": Secret.from_env_var("API_KEY"),
            "X-Client-ID": "my-client-id",
        },
    )

etc etc. Correct?

[wirs1214-alt]

So all you are asking for @wirs1214-alt is an option to specify your headers similar to these examples:

    # API key authentication
    server_info = StreamableHttpServerInfo(
        url="https://my-mcp-server.com",
        headers={"X-API-Key": Secret.from_env_var("API_KEY")},
    )
    # Multiple headers
    server_info = StreamableHttpServerInfo(
        url="https://my-mcp-server.com",
        headers={
            "X-API-Key": Secret.from_env_var("API_KEY"),
            "X-Client-ID": "my-client-id",
        },
    )

etc etc. Correct?

Yes, that's correct. I think this feature should not affect the standardized design of MCP either.

[vblagoje]

Exactly @wirs1214-alt , low impact, doesn't affect our OAuth mcp roadmap, I'll add this today and release new mcp-haystack package!