MCP Client -> Server authentication just using a provided access token

[HarrisonUnifyAI]

Question

I am trying to authenticate with an MCP server that is expecting the standard {"Authorization": f"Bearer {access_token}"} header. I have written a simple httpx.Auth implementation for this purpose, but am still failing to authenticate. Is something like this not intended to work? I verified that "auth_flow" is being called.

class AuthWithToken(httpx.Auth):
    def __init__(self, token: str):
        self.token = token

    def auth_flow(self, request):
        request.headers['Authorization'] = f'Bearer {self.token}'
        yield request

auth = AuthWithToken(auth_token) if auth_token else None
        # Connect to a streamable HTTP server
        async with streamablehttp_client(self.address, auth=auth) as (
            read_stream,
            write_stream,
            _,
        )...

Additional Context

No response

[caravin]

I was checking for this support.
FastMCP's client implementation seems to support passing a bearer token (https://gofastmcp.com/clients/auth/bearer) but I couldn't find a similar support here.

I actually have a different question: I see we have fastmcp implementation for server sdk but there is no such implementation for client sdk. Is there a reason for that? Are we expected to rely on FastMCP2.0 for client sdk?

[HarrisonUnifyAI]

In my case they hadn't yet implemented the correct token support but for anyone else needing it the above httpx.Auth implementation does work!