fix: set MCP error flag for tool error payloads#95
Merged
Conversation
Treat JSON tool responses with status=error as MCP tool errors so clients receive isError=true. Adds protocol-level regression coverage for invalid get_abstract IDs. Fixes #92
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fixes #92
Summary
status: "error"as MCP tool errors at the server boundary.isError: true.get_abstractnot-found responses.Root cause
Tool handlers returned JSON error payloads as normal text content. The MCP Python SDK normalizes returned content with
isError: false; it only setsisError: truewhen the registered tool callback raises/returns an SDK error result. So clients checking the MCP flag saw a successful tool call with an error-looking body.Tests
uv run pytest tests/test_mcp_tool_error_semantics.py::test_get_abstract_not_found_sets_mcp_is_error -quv run pytest tests/tools/test_get_abstract.py tests/test_mcp_tool_error_semantics.py -quv run pytest -q