how to get http request headers in mcp tools logic when i use streamable http mode to run mcp server ?

[kelify]

i want to create a mcp server base on streamablehttp_stateless running mode(https://github.com/modelcontextprotocol/python-sdk/blob/main/examples/servers/simple-streamablehttp-stateless/mcp_simple_streamablehttp_stateless/server.py example code), but i can not find any mothed to get http request msg in the tools logic. so how can i get the http request headers msg in the tools define function ?

[viczommers]

+1 bump

[viczommers]

I figured out this clutch fix for streamable http - I just wanted to verify some header data in my db
here is just code example for authorization bearer check.
you can build on top of it to parse header into meta (mcp.get_context().request_context.meta) or EventStore / store_event()

Since we cant pass middleware to FastMCP I looked at mcp.server.auth
Also take a look at this example examples/servers/simple-auth/mcp_simple_auth

from mcp.server.auth.settings import AuthSettings, ClientRegistrationOptions
from mcp.server.auth.provider import OAuthAuthorizationServerProvider, AccessToken
from pydantic import AnyHttpUrl
from mcp.server.auth.middleware.auth_context import get_access_token

# Create a simple auth provider that just checks for bearer token
class SimpleBearerAuthProvider(OAuthAuthorizationServerProvider):
    async def load_access_token(self, token: str):
        if token:
            try:
                return AccessToken(
                        token=token,
                        client_id="test-client",  # For testing purposes
                        scopes=["api"],
                        expires_at=None
                    )
            except Exception as e:
                return None
        return None

# Create auth settings
auth_settings = AuthSettings(
    issuer_url=AnyHttpUrl("http://localhost:8000"),
    client_registration_options=ClientRegistrationOptions(
        enabled=False,  # Disable client registration
        valid_scopes=["api"],
        default_scopes=["api"],
    ),
    required_scopes=["api"],
)

# Create auth provider instance
auth_provider = SimpleBearerAuthProvider()
mcp = FastMCP(
        name="MCP Server",
        stateless_http=True,
        auth=auth_settings,
        auth_server_provider=auth_provider,
    )
@mcp.tool
async def test_tool() -> JSONResponse:
    access_token = get_access_token().token
    params = {
        "api_key": access_token,
    }

etc...

[alex00127]

Can we directly access the contents of the header, such as the Bearer token?

[AnandShivansh]

@viczommers How to pass the meta from the mcp client to get it in mcp.get_context().request_context.meta?

[aqz5253]

I am newbie to MCP and Agents:

Does anyone know how we can access the bearer token using this method? My use case needs to pass the access_token for another API (Google Calendar) to get access to the user data. Tools need this to fetch the information. I am trying to pass the access token through a custom class

class AuthenticatedMultiServerMCPClient(MultiServerMCPClient):
async def _call_server(self, server, message, *args, **kwargs):
token = current_token.get(None)
if token and self._servers[server]["transport"] == "streamable_http":
self._servers[server]["headers"] = {
"Authorization": f"Bearer {token}"
}
return await super()._call_server(server, message, *args, **kwargs)

But when we call get.tools() there is no header passed which breaks the code.

[josiahdc]

You can pull the header from the MCP supplied context object if you're running a streamable-http server

from fastmcp import FastMCP, Context

mcp = FastMCP()


@mcp.tool(description="prints a header, concatenates it with an agent's input, and returns the result")
async def header_puller(context: Context, agent_supplied_arg: str) -> str:
    example_header = context.request_context.request.headers.get("example-header")
    print(example_header)
    result = f"header: {example_header}, agent input: {agent_supplied_arg}"
    return result

app = mcp.streamable_http_app()

[maxisbey]

Closing as @josiahdc's suggestion should solve the original issue. If it doesn't please feel free to re-open the issue.

[aryan2621]

You can pull the header from the MCP supplied context object if you're running a streamable-http server

from fastmcp import FastMCP, Context

mcp = FastMCP()

@mcp.tool(description="prints a header, concatenates it with an agent's input, and returns the result")
async def header_puller(context: Context, agent_supplied_arg: str) -> str:
example_header = context.request_context.request.headers.get("example-header")
print(example_header)
result = f"header: {example_header}, agent input: {agent_supplied_arg}"
return result

app = mcp.streamable_http_app()

But this feature is on fastmcp package , cant we have it on the python mcp sdk itself ?