perf(mcp): cache MCP tool list per run instead of re-listing before each call#955
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Pull request overview
This PR improves MCP tool invocation performance by memoizing McpClient.list_tools() so tool discovery/schema is fetched once per client lifetime (effectively once per run/resume), instead of re-listing before each tool call. It also updates MCP tool documentation and expands the MCP client test suite to cover caching, forced refresh, and cache clearing on disposal.
Changes:
- Cache
McpClient.list_tools()results with an opt-outforce_refresh=True, and clear the cache ondispose(). - Update MCP tool/schema-refresh documentation to reflect once-per-run tool-list caching behavior.
- Add/adjust tests to validate caching semantics,
force_refresh, and disposal behavior; bump package version to0.13.14.
Reviewed changes
Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
src/uipath_langchain/agent/tools/mcp/mcp_client.py |
Adds in-memory tool-list caching and clears it on dispose. |
src/uipath_langchain/agent/tools/mcp/mcp_tool.py |
Updates schema-refresh docs to reflect cached tool discovery. |
src/uipath_langchain/agent/tools/mcp/claude.md |
Documents once-per-run tool-list caching semantics and limitations. |
tests/agent/tools/test_mcp/test_mcp_client.py |
Updates/extends tests for cached list_tools, force refresh, and dispose cache clearing. |
tests/agent/tools/test_mcp/claude.md |
Updates test suite documentation to include new caching tests. |
pyproject.toml |
Bumps package version to 0.13.14. |
uv.lock |
Updates lockfile for the version bump (and changes exclude-newer). |
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…ach call list_tools() is memoized on McpClient and cleared on dispose(), so the live tool list/schema is fetched once per run rather than before every tool call. A resumed run builds a fresh client and re-fetches; force_refresh=True bypasses the cache. The cached self-heal still evaluates against a list refreshed once per run (and per resume) instead of on every invocation.
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edis-uipath
approved these changes
Jun 30, 2026
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McpClient: fetched once per run instead of before every tool calldispose(), so a resumed run uses a fresh client and re-fetches onceforce_refresh=Trueforces a live re-query when neededlist_tools()calls now issue a single RPC; added force-refresh and dispose-clears-cache cases