MCP client not able to initiate StdioServerParameters while running in Jupyter Notebook

[kdheeraz]

while initiating StdioServerParameters in jupyter notebook there is an Exception from subprocess.Popen.
Exception is : UnsupportedOperation fileno

Same code works in idle and with quart server.

OS : windows 11
Python version: 3.11

[Conchylicultor]

Same issue. It seems like Google Colab / Jupyter notebook mock the sys.stderr, sys.stdout streams, making it incompatible with MCP. Example of traceback:

• https://gist.github.com/Conchylicultor/b4b4d737da59f1da0d5ef81031279510

  UnsupportedOperation: fileno

• https://gist.github.com/Conchylicultor/9b31dc47ac99532e783f7c9d9d7518a6

  AttributeError: 'OutStream' object has no attribute 'buffer'

Reproduction using: https://github.com/modelcontextprotocol/servers/tree/main/src/time

import asyncio
import mcp_server_time

asyncio.run(mcp_server_time.serve())  # AttributeError: 'OutStream' object has no attribute 'buffer'

Raised by:

/usr/local/lib/python3.11/dist-packages/mcp/server/stdio.py in stdio_server(stdin, stdout)
     47         stdin = anyio.wrap_file(TextIOWrapper(sys.stdin.buffer, encoding="utf-8"))
     48     if not stdout:
---> 49         stdout = anyio.wrap_file(TextIOWrapper(sys.stdout.buffer, encoding="utf-8"))

[savvaki]

I have the same issue

[felixweinberger]

Hi thanks for reporting this issue @kdheeraz could you provide a minimal runnable example that isolates the issue you're seeing?

[kikaDev404]

I have the same issue

[tomityrrell]

For a quick fix, please see this comment from a related issue on langchain. Basically, you can pass errlog=None to mcp.client.stdio.stdio_client to avoid this issue in a Jupyter notebook.