`simple-auth` is not working as expected

Vergleiche examples/servers/simple-auth/mcp_simple_auth/server.py mit der simple-auth README und reproduziere die Befehle aus den drei Terminals mit streamable-http. Überprüfe die Verarbeitung der Server-URL und stelle sicher, dass mcp-simple-auth-client erfolgreich eine Verbindung am dokumentierten Endpoint herstellt; das separate TODO befindet sich in simple_auth_provider.py bei ungefähr Zeile 268.

Initial Checks

• I confirm that I'm using the latest version of MCP Python SDK
• I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue

Description

I am trying to follow the example as described in examples/servers/simple-auth. However, when running the mcp-simple-auth-client I am getting the following error (and I know how to fix it):

$ MCP_SERVER_PORT=8000 MCP_TRANSPORT_TYPE=streamable-http uv run mcp-simple-auth-client
🚀 Simple MCP Auth Client
Connecting to: http://localhost:8000/mcp
Transport type: streamable-http
🔗 Attempting to connect to http://localhost:8000/mcp...
🖥️  Started callback server on http://localhost:3030
📡 Opening StreamableHTTP transport connection with auth...
🤝 Initializing MCP session...
⚡ Starting session initialization...
❌ Failed to connect: unhandled errors in a TaskGroup (1 sub-exception)
  + Exception Group Traceback (most recent call last):
  |   File "/home/python-sdk/examples/clients/simple-auth-client/mcp_simple_auth_client/main.py", line 230, in connect
  |     async with streamable_http_client(url=self.server_url, http_client=custom_client) as (
  |   File "/usr/lib/python3.12/contextlib.py", line 231, in __aexit__
  |     await self.gen.athrow(value)
  |   File "/home/python-sdk/src/mcp/client/streamable_http.py", line 563, in streamable_http_client
  |     async with (
  |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 772, in __aexit__
  |     raise BaseExceptionGroup(
  | ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)
  +-+---------------- 1 ----------------
    | Traceback (most recent call last):
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 101, in map_httpcore_exceptions
    |     yield
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 394, in handle_async_request
    |     resp = await self._pool.handle_async_request(req)
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection_pool.py", line 256, in handle_async_request
    |     raise exc from None
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection_pool.py", line 236, in handle_async_request
    |     response = await connection.handle_async_request(
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection.py", line 101, in handle_async_request
    |     raise exc
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection.py", line 78, in handle_async_request
    |     stream = await self._connect(request)
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection.py", line 124, in _connect
    |     stream = await self._network_backend.connect_tcp(**kwargs)
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_backends/auto.py", line 31, in connect_tcp
    |     return await self._backend.connect_tcp(
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_backends/anyio.py", line 113, in connect_tcp
    |     with map_exceptions(exc_map):
    |   File "/usr/lib/python3.12/contextlib.py", line 158, in __exit__
    |     self.gen.throw(value)
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_exceptions.py", line 14, in map_exceptions
    |     raise to_exc(exc) from exc
    | httpcore.ConnectError: All connection attempts failed
    |
    | The above exception was the direct cause of the following exception:
    |
    | Traceback (most recent call last):
    |   File "/home/python-sdk/src/mcp/client/streamable_http.py", line 475, in handle_request_async
    |     await self._handle_post_request(ctx)
    |   File "/home/python-sdk/src/mcp/client/streamable_http.py", line 261, in _handle_post_request
    |     async with ctx.client.stream(
    |   File "/usr/lib/python3.12/contextlib.py", line 210, in __aenter__
    |     return await anext(self.gen)
    |            ^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1583, in stream
    |     response = await self.send(
    |                ^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1629, in send
    |     response = await self._send_handling_auth(
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1657, in _send_handling_auth
    |     response = await self._send_handling_redirects(
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1694, in _send_handling_redirects
    |     response = await self._send_single_request(request)
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1730, in _send_single_request
    |     response = await transport.handle_async_request(request)
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 393, in handle_async_request
    |     with map_httpcore_exceptions():
    |   File "/usr/lib/python3.12/contextlib.py", line 158, in __exit__
    |     self.gen.throw(value)
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 118, in map_httpcore_exceptions
    |     raise mapped_exc(message) from exc
    | httpx.ConnectError: All connection attempts failed
    +------------------------------------

I think the problem is that the server_url in the examples/servers/simple-auth/mcp_simple_auth/server.py includes the path (the /mcp part) whereas in the README it shows the base URL without the path should be used. Changing this locally fixed the problem for me.

I would also be willing to fix the TODO in examples/servers/simple-auth/mcp_simple_auth/simple_auth_provider.py if that's alright.

Example Code

terminal 1:

uv run mcp-simple-auth-as --port=9000


terminal 2:

uv run mcp-simple-auth-rs --port=8001 --auth-server=http://localhost:9000 --transport=streamable-http


terminal 3:

$ MCP_SERVER_PORT=8000 MCP_TRANSPORT_TYPE=streamable-http uv run mcp-simple-auth-client
🚀 Simple MCP Auth Client
Connecting to: http://localhost:8000/mcp
Transport type: streamable-http
🔗 Attempting to connect to http://localhost:8000/mcp...
🖥️  Started callback server on http://localhost:3030
📡 Opening StreamableHTTP transport connection with auth...
🤝 Initializing MCP session...
⚡ Starting session initialization...
❌ Failed to connect: unhandled errors in a TaskGroup (1 sub-exception)
  + Exception Group Traceback (most recent call last):
  |   File "/home/python-sdk/examples/clients/simple-auth-client/mcp_simple_auth_client/main.py", line 230, in connect
  |     async with streamable_http_client(url=self.server_url, http_client=custom_client) as (
  |   File "/usr/lib/python3.12/contextlib.py", line 231, in __aexit__
  |     await self.gen.athrow(value)
  |   File "/home/python-sdk/src/mcp/client/streamable_http.py", line 563, in streamable_http_client
  |     async with (
  |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 772, in __aexit__
  |     raise BaseExceptionGroup(
  | ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)
  +-+---------------- 1 ----------------
    | Traceback (most recent call last):
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 101, in map_httpcore_exceptions
    |     yield
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 394, in handle_async_request
    |     resp = await self._pool.handle_async_request(req)
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection_pool.py", line 256, in handle_async_request
    |     raise exc from None
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection_pool.py", line 236, in handle_async_request
    |     response = await connection.handle_async_request(
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection.py", line 101, in handle_async_request
    |     raise exc
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection.py", line 78, in handle_async_request
    |     stream = await self._connect(request)
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_async/connection.py", line 124, in _connect
    |     stream = await self._network_backend.connect_tcp(**kwargs)
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_backends/auto.py", line 31, in connect_tcp
    |     return await self._backend.connect_tcp(
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_backends/anyio.py", line 113, in connect_tcp
    |     with map_exceptions(exc_map):
    |   File "/usr/lib/python3.12/contextlib.py", line 158, in __exit__
    |     self.gen.throw(value)
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpcore/_exceptions.py", line 14, in map_exceptions
    |     raise to_exc(exc) from exc
    | httpcore.ConnectError: All connection attempts failed
    |
    | The above exception was the direct cause of the following exception:
    |
    | Traceback (most recent call last):
    |   File "/home/python-sdk/src/mcp/client/streamable_http.py", line 475, in handle_request_async
    |     await self._handle_post_request(ctx)
    |   File "/home/python-sdk/src/mcp/client/streamable_http.py", line 261, in _handle_post_request
    |     async with ctx.client.stream(
    |   File "/usr/lib/python3.12/contextlib.py", line 210, in __aenter__
    |     return await anext(self.gen)
    |            ^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1583, in stream
    |     response = await self.send(
    |                ^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1629, in send
    |     response = await self._send_handling_auth(
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1657, in _send_handling_auth
    |     response = await self._send_handling_redirects(
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1694, in _send_handling_redirects
    |     response = await self._send_single_request(request)
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_client.py", line 1730, in _send_single_request
    |     response = await transport.handle_async_request(request)
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 393, in handle_async_request
    |     with map_httpcore_exceptions():
    |   File "/usr/lib/python3.12/contextlib.py", line 158, in __exit__
    |     self.gen.throw(value)
    |   File "/home/python-sdk/.venv/lib/python3.12/site-packages/httpx/_transports/default.py", line 118, in map_httpcore_exceptions
    |     raise mapped_exc(message) from exc
    | httpx.ConnectError: All connection attempts failed
    +------------------------------------

Python & MCP Python SDK

`Python 3.12.3`
`mcp-simple-auth 0.1.0`

and MCP Python SDK:

$ git describe --tags
v1.25.0-180-g5d82649