fix(mcp): keep truncated tool descriptions within the length cap#432
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Alan-Yu-2077 wants to merge 1 commit into
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fix(mcp): keep truncated tool descriptions within the length cap#432Alan-Yu-2077 wants to merge 1 commit into
Alan-Yu-2077 wants to merge 1 commit into
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truncateMcpToolDescription sliced to MAX_MCP_TOOL_DESCRIPTION_LENGTH and then appended the "… [truncated]" marker, so any over-limit description returned 2048 + marker characters and contradicted the documented clamp. Reserve the marker length inside the cap so the returned string is at most MAX_MCP_TOOL_DESCRIPTION_LENGTH characters, and add regression tests at and just past the boundary.
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Summary
truncateMcpToolDescription()is documented as clamping MCP tool descriptions toMAX_MCP_TOOL_DESCRIPTION_LENGTH(2048) characters, but for any over-limit input it sliced the string to 2048 characters and then appended the"… [truncated]"marker. The returned string was therefore 2061 characters — longer than the advertised cap.This fix reserves the marker length inside the cap, so an over-limit description is sliced to
MAX_MCP_TOOL_DESCRIPTION_LENGTH - marker.lengthbefore the marker is appended. The returned string is now at mostMAX_MCP_TOOL_DESCRIPTION_LENGTHcharacters.Fixes #423
Test plan
Added
tests/mcp/truncate.spec.tscovering the boundary:MAX_MCP_TOOL_DESCRIPTION_LENGTHcharacters and still ends with the marker;Full suite (
npm test) stays green.