[basilalshukaili]

Summary

call_tool in src/time/src/mcp_server_time/server.py wraps its entire body in try … except Exception as e: raise ValueError(…). McpError (raised by get_zoneinfo for unknown timezone names) is a subclass of Exception, so it was silently caught and re-raised as a plain ValueError. This discarded the structured INVALID_PARAMS error code that the MCP transport layer uses to distinguish client errors from server faults — causing MCP clients that inspect error codes to see an opaque server error instead of a proper "invalid argument" response.

Fix

Add an explicit except McpError: raise guard before the broad handler so McpError propagates to the transport layer with its code intact:

except McpError:
    raise           # preserve INVALID_PARAMS / structured error code
except Exception as e:
    raise ValueError(f"Error processing mcp-server-time query: {str(e)}")

Also fixes a minor description typo: "Get current time in a specific timezones" → "Get current time in a specific timezone".

Tests

Added three assertions that verify McpError carries INVALID_PARAMS when an invalid timezone is supplied to get_current_time and both positions of convert_time. These tests fail on the previous code (a ValueError is raised instead of McpError).

uv run pytest src/time/test/time_server_test.py  # 41 passed

[basilalshukaili]

Following up here — all checks are green. This is a small, targeted fix to preserve the INVALID_PARAMS code that the generic call_tool handler was overwriting. Happy to tweak if anything needs changing. Thanks for taking a look!

[LuuOW]

Technical audit: Verified MCP server implementation for consistency with current SDK patterns.

[cliffhall]

Thank you for this pull request, and apologies for the long wait for a response.

Since it was opened, the reference servers have been rebuilt for the 2026-07-28 MCP specification (#4857) and released as v2 (2.0.0 on npm for the TypeScript servers, 2026.10.19 on PyPI for the Python servers). The code this PR changes has been replaced, and the behavior it addresses has either been fixed in v2 or no longer exists in the same form.

This is not a judgment on the change or on you; it's a consequence of the code it targets having been replaced. If the problem still happens on v2, please open a fresh issue with the version you're running and steps to reproduce. Note that this repository now accepts contributions as issues rather than pull requests from anyone but its maintainers; see CONTRIBUTING.md.

This is part of the backlog triage in #4875.