camel [BUG] Failed to connect DLL MCP tool

Required prerequisites

[x] I have read the documentation https://camel-ai.github.io/camel/camel.html.
[x] I have searched the Issue Tracker and Discussions that this hasn't already been reported. (+1 or comment there if it has.)
[ ] Consider asking first in a Discussion.

What version of camel are you using?

0.2.78

System information

3.10.19 | packaged by Anaconda, Inc. | (main, Oct 21 2025, 16:41:31) [MSC v.1929 64 bit (AMD64)] win32 0.2.78 using conda as environment and pip install caml-ai[all]

Problem description

I am based on I wrote a document translation MCP tool (STDIO) in NET 8.0, but I couldn't connect to my MCP tool properly using the official example:

config_path = Path(__file__).parent / "mcp_test.json"
mcp_toolkit = MCPToolkit(config_path=str(config_path))

try:
    await mcp_toolkit.connect()

MCP config json:

{
  "mcpServers": {
    "wordmcpro": {
      "command": "dotnet",
      "args": [
        "D:/Project/CSharp/WordMCPro/bin/Debug/net8.0/WordMCPro.dll"
      ],
      "timeout": 300000
    }
  }
}

I have test my mcp tool in cherry studio, it works fine.

Reproducible example code

The Python snippets:

config_path = Path(__file__).parent / "mcp_test.json"
mcp_toolkit = MCPToolkit(config_path=str(config_path))

try:
    await mcp_toolkit.connect()

Steps to reproduce:

compile C# mcp tools code as .dll file in .NET 8.0
dotnet XXX.dll for testing mcp runing status, if OK, close it
using offical code to connect mcp tools

Traceback

Traceback (most recent call last):
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\anyio\streams\memory.py", line 111, in receive
    return self.receive_nowait()
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\anyio\streams\memory.py", line 106, in receive_nowait
    raise WouldBlock
anyio.WouldBlock

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\tasks.py", line 234, in __step
    result = coro.throw(exc)
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\camel\utils\commons.py", line 998, in async_wrapper
    return await func(*args, **kwargs)
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\camel\toolkits\mcp_toolkit.py", line 448, in _connect_all_clients
    await self._exit_stack.enter_async_context(client)
  File "C:\Users\240508\.conda\envs\owl\lib\contextlib.py", line 619, in enter_async_context
    result = await _cm_type.__aenter__(cm)
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\camel\utils\mcp_client.py", line 288, in __aenter__
    await self._establish_connection()
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\camel\utils\mcp_client.py", line 318, in _establish_connection
    await self._session.initialize()
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\mcp\client\session.py", line 152, in initialize
    result = await self.send_request(
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\mcp\shared\session.py", line 272, in send_request
    response_or_error = await response_stream_reader.receive()
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\anyio\streams\memory.py", line 119, in receive
    await receive_event.wait()
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\locks.py", line 214, in wait
    await fut
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\futures.py", line 285, in __await__
    yield self  # This tells Task to wait for completion.
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\tasks.py", line 304, in __wakeup
    future.result()
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\futures.py", line 196, in result
    raise exc
asyncio.exceptions.CancelledError: Cancelled via cancel scope 17e78a55de0

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\camel\toolkits\mcp_toolkit.py", line 411, in connect
    await asyncio.wait_for(
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\tasks.py", line 445, in wait_for
    return fut.result()
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\futures.py", line 196, in result
    raise exc
asyncio.exceptions.CancelledError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "D:\Project\Python\owl-main\examples\run_mcp.py", line 178, in <module>
    asyncio.run(main())
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\nest_asyncio.py", line 30, in run
    return loop.run_until_complete(task)
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\nest_asyncio.py", line 98, in run_until_complete
    return f.result()
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\futures.py", line 201, in result
    raise self._exception.with_traceback(self._exception_tb)
  File "C:\Users\240508\.conda\envs\owl\lib\asyncio\tasks.py", line 232, in __step
    result = coro.send(None)
  File "D:\Project\Python\owl-main\examples\run_mcp.py", line 150, in main
    await mcp_toolkit.connect()
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\camel\utils\commons.py", line 998, in async_wrapper
    return await func(*args, **kwargs)
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\camel\toolkits\mcp_toolkit.py", line 433, in connect
    raise MCPConnectionError(error_msg)
camel.toolkits.mcp_toolkit.MCPConnectionError: Connection timeout after 30.0s. One or more MCP servers are not responding. Please check if the servers are running and accessible.
Exception ignored in: <async_generator object MCPClient._create_transport at 0x0000017E3177BD40>
RuntimeError: async generator ignored GeneratorExit
Exception ignored in: <async_generator object stdio_client at 0x0000017E78980EC0>
Traceback (most recent call last):
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\mcp\client\stdio\__init__.py", line 182, in stdio_client
  File "C:\Users\240508\.conda\envs\owl\lib\site-packages\anyio\_backends\_asyncio.py", line 745, in __aexit__
RuntimeError: no running event loop

Expected behavior

Normal connection and use. Looking forward that the developer can help me solve this problem. Thank you very much!

Additional context

No response

Nov 06 '25 01:11 Charmnut

AnyBody here？

Nov 07 '25 07:11 Charmnut

thanks @Charmnut for reporting this issue and sorry for the delayed response, we will check this and back to you ASAP

Nov 10 '25 03:11 Wendong-Fan

Thanks @Charmnut, it looks like the timeout is not properly setting up, from camel.toolkits.mcp_toolkit.MCPConnectionError: Connection timeout after 30.0s. I suspect that he 30-second connection timeout might be too short for .NET DLL startup. This could be the main issue. Could you try with

 mcp_toolkit = MCPToolkit(
      config_path=str(config_path),
      timeout=300.0 
  )

Nov 14 '25 08:11 MuggleJinx

Thanks @Charmnut, it looks like the timeout is not properly setting up, from camel.toolkits.mcp_toolkit.MCPConnectionError: Connection timeout after 30.0s. I suspect that he 30-second connection timeout might be too short for .NET DLL startup. This could be the main issue. Could you try with
 mcp_toolkit = MCPToolkit(
      config_path=str(config_path),
      timeout=300.0 
  )

Firstly, the error time is very fast, less than 30 seconds; secondly, I have set a very long timeout in Json, does it work the same as the code you provided?

Nov 25 '25 10:11 Charmnut