fastmcp.server.openapi Deprecation

[Xenov-X]

Latest versions of fastmcp will result in silent failure at cs_mcp.py#L308

$ python3 cobaltstrike-mcp-server/cs_mcp.py --insecure --transport stdio
/<PATH>/cs_server.py:10: DeprecationWarning: fastmcp.server.openapi is deprecated. Import from fastmcp.server.providers.openapi instead.
  from fastmcp.server.openapi import RouteMap, MCPType
2026-03-13 11:18:19,914 WARNING __main__ - TLS verification disabled; connections will not be validated
2026-03-13 11:18:19,914 INFO __main__ - Starting Cobalt Strike MCP server
2026-03-13 11:18:19,914 INFO __main__ - Authenticating with Cobalt Strike API as 'MCP'
2026-03-13 11:18:20,203 INFO httpx - HTTP Request: POST https://localhost:50443/api/auth/login "HTTP/1.1 200 "
2026-03-13 11:18:20,204 INFO cs_client - Successfully authenticated with Cobalt Strike API


$ echo $?
1                                         

Adding a traceback exception handler to cs_mcp.py highlighted fastmcp not having the experimental attribute

2026-03-13 11:47:07,613 DEBUG cs_client - Cobalt Strike client closed
Traceback (most recent call last):
  File "/PATH/cs_mcp.py", line 330, in <module>
    asyncio.run(main())
    ~~~~~~~~~~~^^^^^^^^
  File "/usr/lib/python3.13/asyncio/runners.py", line 195, in run
    return runner.run(main)
           ~~~~~~~~~~^^^^^^
  File "/usr/lib/python3.13/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/usr/lib/python3.13/asyncio/base_events.py", line 725, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "/PATH/cs_mcp.py", line 308, in main
    await mcp_server.create_server(args.spec_url)
  File "/PATH/cs_server.py", line 53, in create_server
    fastmcp.settings.experimental.enable_new_openapi_parser = True
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/PATH/main.py", line 1026, in __getattr__
    raise AttributeError(f'{type(self).__name__!r} object has no attribute {item!r}')
AttributeError: 'Settings' object has no attribute 'experimental'

Issues overview

• fastmcp.server.openapi is deprecated in favour of fastmcp.server.providers.openapi.
• As of fastmcp v2.14 the experimental openAPI parser has been promoted to standard/default.

Fixes applied

• added basic exception printer to cs_mcp.py if __name__ == "__main__":
• removed references to experimental parser (flags etc)
• bumped minimum version of fastmcp to v2.14.0

Ref: https://github.com/PrefectHQ/fastmcp/releases/tag/v2.14.0