fix(mcp): include exception type in error messages when str(exc) is empty (salvage #19425) - #21292
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…mpty
Some exception classes (e.g. anyio.ClosedResourceError) are raised without
a message argument, so str(exc) returns an empty string. The existing error
format f'{type(exc).__name__}: {exc}' would produce messages like
'MCP call failed: ClosedResourceError: ' with nothing after the colon.
Add _exc_str() helper that falls back to repr(exc) when str(exc) is empty,
and apply it to all 6 MCP error formatting sites (5 tool/prompt/resource
handlers + 1 sampling handler).
Fixes #19417
Contributor
🔎 Lint report:
|
| Rule | Count |
|---|---|
unresolved-import |
1 |
First entries
tests/tools/test_mcp_empty_error_message.py:14: [unresolved-import] unresolved-import: Cannot resolve imported module `pytest`
✅ Fixed issues: none
Unchanged: 3954 pre-existing issues carried over.
Diagnostics are surfaced as warnings — this check never fails the build.
alt-glitch
added
type/bug
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Closes #19425 via salvage. Fixes #19417.
Summary
anyio.ClosedResourceErrorand some other exceptions are raised with no message —str(exc)is"". The existing error format producesMCP call failed: ClosedResourceError:with nothing after the colon. Add_exc_str()helper that falls back torepr(exc)whenstr(exc)is empty. Apply to all 6 MCP error formatting sites.Validation
scripts/run_tests.sh tests/tools/test_mcp_empty_error_message.py→ 6 passed.Original author: @liuhao1024.