fix: MCP component auto reset issue in non Tool Mode

[edwinjosechittilappilly]

This pull request refines the logic for updating the build configuration in the MCPComponent to avoid unnecessary UI updates and improve efficiency when switching servers and handling tool options. The main improvements focus on only resetting or updating tool-related options when the server actually changes, and on better handling of the "Tool Mode" state.

Optimizations for tool dropdown and server switching:

• Added a fast path to skip unnecessary updates to tool options if the server hasn't changed and options already exist, improving UI responsiveness.
• Refactored logic to only clear previous tool inputs (remove_non_default_keys) when the server actually changes, preventing unwanted resets.
• Changed the value refresh for the tool dropdown to only occur if the server changed or there are no cached tools, reducing redundant refreshes.

Code cleanup and logic streamlining:

• Moved the determination of "Tool Mode" and its usage to a more logical position, ensuring the dropdown visibility is handled consistently. [1] [2]

Summary by CodeRabbit

• Bug Fixes

  • Enhanced error handling and validation for tool configurations with improved fallback mechanisms.
  • Increased resilience when fetching tool data by preserving visibility state during errors or timeouts.

• Performance

  • Optimized tool configuration updates to skip unnecessary recomputation when server selection hasn't changed.
  • Improved caching behavior with smarter invalidation logic.

[coderabbitai]

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Walkthrough

Both files update MCPToolsComponent logic. The Nvidia Remix.json file replaces the implementation with enhanced caching, error handling, and state management. The mcp_component.py file adds optimization flags to reduce unnecessary recomputation in update_build_config and clarifies tool-selection behavior.

Changes

Cohort / File(s)	Change Summary
Starter Project Configuration src/backend/base/langflow/initial_setup/starter_projects/Nvidia Remix.json	Replaced MCPToolsComponent implementation with substantially updated version featuring enhanced caching resilience, improved error handling, expanded method signatures for state management (_ensure_cache_structure, _validate_schema_inputs, update_tool_list, update_build_config), and new helper methods (process_output_item, _preprocess_schema, _get_session_context) for richer tool invocation and output processing. Code hash changed from 81b1338be859 to 2e303f9666c2.
Core Component Logic src/lfx/src/lfx/components/agents/mcp_component.py	Added fast-path optimization in update_build_config for mcp_server branch using new server_changed and is_in_tool_mode flags to preserve current visibility and options when server hasn't changed. Clarified tool input clearing to only occur on actual server changes, adjusted tool dropdown value refresh behavior, and consolidated decision flow to reduce unnecessary recomputation.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~30 minutes

• The Nvidia Remix.json update involves substantial method enhancements and caching logic changes that require careful verification of error handling paths and state management correctness.
• The mcp_component.py optimization introduces new conditional flags that affect control flow; verify that the fast-path correctly handles edge cases (missing cache, server changes, tool visibility toggling).
• Cross-file consistency: ensure the optimization flags and logic in mcp_component.py align with the enhanced implementation expectations in Nvidia Remix.json.

Possibly related PRs

• feat: Add cache toggle to MCPToolsComponent and tests #9931: Modifies the same MCPToolsComponent caching and tool-selection logic in update_tool_list and update_build_config methods.
• fix: Add output item processing for tool results #10348: Updates MCPToolsComponent in mcp_component.py, including process_output_item and build_output method modifications.
• fix: enable tool mode only if a server is selected #8865: Refactors the same update_build_config method, adjusting tool-mode visibility and server-change handling.

Suggested labels

refactor, lgtm

Suggested reviewers

• lucaseduoli
• Adam-Aghili

Pre-merge checks and finishing touches

Important

Pre-merge checks failed

Please resolve all errors before merging. Addressing warnings is optional.

❌ Failed checks (1 error, 2 warnings)

Check name	Status	Explanation	Resolution
Test Coverage For New Implementations	❌ Error	PR introduces significant changes to MCPComponent without corresponding test files for new functionality or bug fixes.	Add test_mcp_component.py with unit tests for update_build_config fast-path, tools_metadata preservation, _tool_cache error handling, and integration tests.
Test Quality And Coverage	⚠️ Warning	The PR lacks comprehensive test coverage for MCP component changes including refactored update_build_config method and cache handling logic.	Add pytest test file covering update_build_config, remove_non_default_keys, build_output, and cache invalidation with both success and error paths.
Test File Naming And Structure	⚠️ Warning	Pull request modifies mcp_component.py and MCPToolsComponent without including any test files following pytest patterns.	Add test_mcp_component.py with pytest tests for fast-path optimization, cache invalidation, server change detection, and error handling scenarios.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title 'fix: MCP component auto reset issue in non Tool Mode' clearly matches the core objective of preventing unnecessary UI resets and improving efficiency in the MCPComponent when handling tool options and server changes.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Excessive Mock Usage Warning	✅ Passed	The pull request contains no test files, making this assessment not applicable. No tests exist to evaluate for excessive mock usage.

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[erichare]

LGTM!