`simple-auth` is not working as expected

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

examples/servers/simple-auth/mcp_simple_auth/server.py と simple-auth README を比較し、streamable-http を使用して 3 つのターミナルのコマンドを再現してください。サーバー URL の処理を確認し、mcp-simple-auth-client がドキュメントに記載されたエンドポイントに正常に接続できることを検証してください。別の TODO は simple_auth_provider.py の 268 行目付近にあります。