Skip to content

docs(auth): add section on custom header passthrough in FastApiMCP #248

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
sarang-pratham wants to merge 1 commit into
base: main
Choose a base branch
from
Open

docs(auth): add section on custom header passthrough in FastApiMCP #248

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 16 additions & 0 deletions docs/advanced/auth.mdx
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,22 @@ mcp.mount_http()

For a complete working example of authorization header, check out the [Token Passthrough Example](https://github.com/tadata-org/fastapi_mcp/blob/main/examples/08_auth_example_token_passthrough.py) in the examples folder.

### Forwarding Custom HTTP Headers

By default, `FastApiMCP` forwards the `authorization` header from the incoming MCP request into each tool invocation.
However, the server also supports forwarding **any additional headers** you choose. This is controlled by the `headers` parameter in `FastApiMCP`, which acts as an allowlist.

```python
from fastapi_mcp import FastApiMCP

mcp = FastApiMCP(
app,
name="MCP With Custom headers Passthrough",
headers=["authorization", "user_id", "some-other-custom-header"],
)
mcp.mount_http()
```

## OAuth Flow

FastAPI-MCP supports the full OAuth 2 flow, compliant with [MCP Spec 2025-03-26](https://modelcontextprotocol.io/specification/2025-03-26/basic/authorization).
Expand Down