fix(core): prevent MCP tool wiping on background discovery failures#25937
fix(core): prevent MCP tool wiping on background discovery failures#25937spencer426 wants to merge 1 commit into
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Summary of ChangesHello, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request addresses a critical issue where MCP tools were being inadvertently removed from the registry due to background refresh failures. By ensuring that discovery errors are properly propagated rather than masked as an empty tool list, the system now maintains existing tool registrations during periods of network instability or timeouts. Highlights
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Code Review
This pull request updates the discoverTools function in packages/core/src/tools/mcp-client.ts to explicitly re-throw errors encountered during the discovery process. Correspondingly, the test suite in packages/core/src/tools/mcp-client.test.ts has been updated to verify that tools are no longer removed from the registry when a discovery failure occurs. I have no feedback to provide as there were no review comments.
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Size Change: +17 B (0%) Total Size: 33.7 MB
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Summary
This PR fixes an issue where discovered tools from an MCP server are erroneously wiped from the
ToolRegistryif a background refresh operation fails due to network latency or an idle timeout.Details
When an MCP server's background connection is dropped (e.g. idle timeout during a long API request), an attempted background
discoverToolscould fail with a generic network error. Previously,discoverToolscaught this error and returned an empty array[]instead of throwing.refreshToolsinterpreted this empty array as 0 tools on the server and aggressively removed the server's tools from the CLI's registry usingremoveMcpToolsByServer().This PR updates
discoverToolsto correctly re-throw the error when it is not aMethodNotFounderror. This preserves the existing tools in theToolRegistryand avoids the confusing "tool could no longer be found" error when the session later tries to use the registered tool. A regression test case was also added to ensure this behavior is enforced.Related Issues
Fixes https://github.com/google-gemini/maintainers-gemini-cli/issues/1635
How to Validate
packages/core/src/tools/mcp-client.test.tsfor handling graceful tool refresh errors.npm run test -w @google/gemini-cli-core -- src/tools/mcp-client.test.tsnpm run lintandnpm run typecheckPre-Merge Checklist