fix: validate MCP tool exists before execution #7632

roomote · 2025-09-03T16:48:28Z

Summary

This PR addresses Issue #7631 by adding validation to prevent Roo from calling MCP tools that don't exist on a server.

Problem

Previously, when the model requested a non-existent tool on an MCP server, the request would be sent to the server anyway, resulting in a raw error response being displayed to the user.

Solution

Added validation that checks if the requested tool exists on the MCP server before attempting to execute it. If the tool doesn't exist:

The request is rejected immediately without contacting the MCP server
A helpful error message is displayed listing all available tools on that server
The model can then retry with a valid tool name

Changes

Added validateToolExists function in useMcpToolTool.ts to check tool availability
Integrated validation into the tool execution flow
Added comprehensive error messages with available tool listings
Added i18n support for the new error messages
Added unit tests covering multiple scenarios (unknown tools, servers with no tools, valid tools)

Testing

✅ All existing tests pass
✅ Added 3 new test cases for tool validation
✅ Manually tested with MCP servers
✅ Type checking passes
✅ Linting passes

Fixes #7631

Important

Adds validation in useMcpToolTool.ts to check MCP tool existence before execution, with error handling and i18n support.

Behavior:
- Adds validateToolExists in useMcpToolTool.ts to check tool existence on MCP server before execution.
- Rejects requests for non-existent tools with error messages listing available tools.
- Handles unknown servers by listing available servers.
Error Handling:
- Displays error messages for unknown tools and servers in responses.ts.
- Adds i18n support for error messages in multiple languages.
Testing:
- Adds unit tests in useMcpToolTool.spec.ts for tool validation scenarios (unknown tools, no tools, valid tools).
- Ensures all existing tests pass.

^{This description was created by}^{for 97945bd. You can customize this summary. It will automatically update as commits are pushed.}

- Add validation to check if requested tool exists on the MCP server - Provide helpful error messages with list of available tools - Prevent sending requests for non-existent tools to MCP servers - Add comprehensive tests for the new validation logic Fixes #7631

roomote

Reviewed my own code. Found it disturbingly functional. Clearly a glitch in the matrix.

roomote · 2025-09-03T16:54:23Z

src/core/tools/useMcpToolTool.ts

+
+		if (!server) {
+			// Server not found - this will be caught later in the flow
+			return { isValid: true }


Is this intentional? When the server is not found, returning { isValid: true } allows execution to continue. Should we fail validation here instead to prevent unnecessary API calls?

roomote · 2025-09-03T16:54:23Z

src/core/tools/useMcpToolTool.ts

+	} catch (error) {
+		// If there's an error during validation, log it but don't block the tool execution
+		// The actual tool call might still fail with a proper error
+		console.error("Error validating MCP tool existence:", error)


Consider surfacing validation errors to users for better debugging visibility. The error is only logged to console which might make troubleshooting harder.

roomote · 2025-09-03T16:54:23Z

src/core/tools/__tests__/useMcpToolTool.spec.ts

 			expect(mockHandleError).toHaveBeenCalledWith("executing MCP tool", error)
 		})
+
+		it("should reject unknown tool names", async () => {


Consider adding a test case for when the MCP hub itself is unavailable to ensure the fallback behavior works correctly.

…d tests

daniel-lxs

LGTM

mrubens · 2025-09-04T16:32:34Z

src/core/tools/useMcpToolTool.ts

+
+		if (!toolExists) {
+			// Tool not found - provide list of available tools
+			const availableToolNames = server.tools.map((tool) => tool.name)


Does this take into account tools that the user has disabled?

take into account tools that the user has disabled

@mrubens

After the bug fix release, I see that disabled tools are being ignored, and the prompt mentions all tools, including the disabled ones.

I have additionally checked the system prompt, and everything is correct there - disabled tools are not included in the description.

- Check enabledForPrompt property in validateToolExists function - Reject disabled tools with appropriate error message - Show only enabled tools in error message when tool is disabled Addresses PR feedback about checking for disabled tools

ellipsis-dev · 2025-09-04T20:48:04Z

src/core/tools/useMcpToolTool.ts

+			cline.recordToolError("use_mcp_tool")
+			await cline.say(
+				"error",
+				`Tool '${toolName}' on server '${serverName}' is disabled. Available enabled tools: ${enabledToolNames.length > 0 ? enabledToolNames.join(", ") : "No enabled tools available"}`,


Consider using the i18n translation function (t()) for the disabled tool error message instead of an inline string. For consistency with the tool-not-found error (which uses t('mcp:errors.toolNotFound')), refactor this error message (and the "No enabled tools available" text) to use a translation key (e.g., t('mcp:errors.toolDisabled', { toolName, serverName, enabledTools: enabledToolNames.join(", ") })) so that the message supports multiple languages.

Suggested change

`Tool '${toolName}' on server '${serverName}' is disabled. Available enabled tools: ${enabledToolNames.length > 0 ? enabledToolNames.join(", ") : "No enabled tools available"}`,

t('mcp:errors.toolDisabled', { toolName, serverName, enabledTools: enabledToolNames.length > 0 ? enabledToolNames.join(", ") : "No enabled tools available" }),

^{This comment was generated because it violated a code review rule: irule_C0ez7Rji6ANcGkkX.}

- Replace hardcoded error message with t() translation function - Add toolDisabled translation key to all 17 locale files - Maintains proper placeholder variables for code integration

* Follow symlinks in rooignore checks (RooCodeInc#7405) * Sonic -> Grok Code Fast (RooCodeInc#7426) * chore: add changeset for v3.26.0 (RooCodeInc#7428) * Changeset version bump (RooCodeInc#7429) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Matt Rubens <[email protected]> * feat: Add Vercel AI Gateway provider integration (RooCodeInc#7396) Co-authored-by: daniel-lxs <[email protected]> Co-authored-by: cte <[email protected]> * feat: Enable on-disk storage for Qdrant vectors and HNSW index (RooCodeInc#7182) * fix: use anthropic protocol for token counting when using anthropic models via Vercel AI Gateway (RooCodeInc#7433) - Added condition in getApiProtocol to return 'anthropic' for vercel-ai-gateway when modelId starts with 'anthropic/' - Added tests for Vercel AI Gateway provider protocol detection This ensures proper token counting for Anthropic models accessed through Vercel AI Gateway, as Anthropic and OpenAI count tokens differently (Anthropic excludes cache tokens from input count, OpenAI includes them). * fix: remove duplicate cache display in task header (RooCodeInc#7443) * Random chat text area cleanup (RooCodeInc#7436) * Update @roo-code/cloud to enable roomote control for cloud agents (RooCodeInc#7446) Co-authored-by: ellipsis-dev[bot] <65095814+ellipsis-dev[bot]@users.noreply.github.com> * Always set remoteControlEnabled to true for cloud agents (RooCodeInc#7448) * chore: add changeset for v3.26.1 (RooCodeInc#7459) * feat: show model ID in API configuration dropdown (RooCodeInc#7423) * feat: update tooltip component to match native VSCode tooltip shadow styling (RooCodeInc#7457) Co-authored-by: Roo Code <[email protected]> Co-authored-by: cte <[email protected]> * Add support for Vercel embeddings (RooCodeInc#7445) Co-authored-by: daniel-lxs <[email protected]> * Remove dot before model display (RooCodeInc#7461) * Update contributors list (RooCodeInc#7109) Co-authored-by: mrubens <[email protected]> * Update 3.26.1 changeset (RooCodeInc#7463) * Changeset version bump (RooCodeInc#7460) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Matt Rubens <[email protected]> * Add type for RooCodeEventName.TaskSpawned (RooCodeInc#7465) * fix: hide .rooignore'd files from environment details by default (RooCodeInc#7369) * fix: change default showRooIgnoredFiles to false to hide ignored files - Changed default value from true to false across all files - Updated tests to reflect the new default behavior - This prevents ignored files from appearing in environment details Fixes RooCodeInc#7368 * fix: update tests to match new showRooIgnoredFiles default * fix: update test expectation to match new showRooIgnoredFiles default value The PR changed the default value of showRooIgnoredFiles from true to false, so the test needs to expect false instead of true when calling formatFilesList. --------- Co-authored-by: Roo Code <[email protected]> Co-authored-by: daniel-lxs <[email protected]> * fix: exclude browser scroll actions from repetition detection (RooCodeInc#7471) - Modified ToolRepetitionDetector to skip repetition detection for browser_action scroll_down and scroll_up actions - Added isBrowserScrollAction() helper method to identify scroll actions - Added comprehensive tests for the new behavior - Fixes issue where multiple scroll actions were incorrectly flagged as being stuck in a loop Resolves: RooCodeInc#7470 Co-authored-by: Roo Code <[email protected]> * Fix GPT-5 Responses API issues with condensing and image support (RooCodeInc#7067) Co-authored-by: ellipsis-dev[bot] <65095814+ellipsis-dev[bot]@users.noreply.github.com> Co-authored-by: Roo Code <[email protected]> Co-authored-by: Hannes Rudolph <[email protected]> * Bump cloud to 0.25.0 (RooCodeInc#7475) * feat: add image generation tool with OpenRouter integration (RooCodeInc#7474) Co-authored-by: Matt Rubens <[email protected]> Co-authored-by: cte <[email protected]> * Make the default image filename more generic (RooCodeInc#7479) * Release v3.26.2 (RooCodeInc#7490) * Support free imagegen (RooCodeInc#7493) * feat: update OpenRouter API to support input/output modalities and filter image generation models (RooCodeInc#7492) * Add padding to image model picker (RooCodeInc#7494) * fix: prevent dirty state on initial mount in ImageGenerationSettings (RooCodeInc#7495) * Changeset version bump (RooCodeInc#7491) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Matt Rubens <[email protected]> * Show console logging in vitests when the --no-silent flag is set (RooCodeInc#7467) By default, all of the tests run in silent mode with monkey-patched the console logging so no console logging will ever appear in test output. This confuses the agent- sometimes it will add console logging to help it debug things, and it won't see the logs that it expects. Adds src/utils/vitest-verbosity.ts to handle verbosity resolution and console logging. Modifies src/vitest.config.ts and webview-ui/vitest.config.ts to integrate the new verbosity control. Removes manual console suppression from src/vitest.setup.ts and webview-ui/vitest.setup.ts as it's now handled dynamically. Co-authored-by: Chris Hasson <[email protected]> * Move @roo-code/cloud to the Roo-Code repo (RooCodeInc#7503) * Refactor the extension bridge (RooCodeInc#7515) * Implement deferred task subscriptions (RooCodeInc#7517) * feat: add optional input image parameter to image generation tool (RooCodeInc#7525) Co-authored-by: Roo Code <[email protected]> Co-authored-by: Daniel Riccio <[email protected]> * feat: sync extension bridge settings with cloud (RooCodeInc#7535) - Use CloudService.getUserSettings() for remoteControlEnabled instead of global state - Update CloudService.updateUserSettings when toggling remote control - Add BridgeOrchestrator.connectOrDisconnect handling in settings update handler - Remove dependency on contentProxy/globalSettings for remote control state --------- Co-authored-by: Roo Code <[email protected]> Co-authored-by: John Richmond <[email protected]> * refactor: flatten image generation settings structure (RooCodeInc#7536) * chore: add changeset for v3.26.3 (RooCodeInc#7541) * Changeset version bump (RooCodeInc#7542) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Matt Rubens <[email protected]> * Mode and provider profile selector (RooCodeInc#7545) * Putting the Roo in Roo-leases (RooCodeInc#7546) * Fix evals (RooCodeInc#7547) * fix: special tokens should not break task processing (

roomote bot requested review from cte, jr and mrubens as code owners September 3, 2025 16:48

github-project-automation bot added this to Roo Code Roadmap and Roo Code Roadmap Sep 3, 2025

github-project-automation bot moved this to Triage in Roo Code Roadmap Sep 3, 2025

github-project-automation bot moved this to New in Roo Code Roadmap Sep 3, 2025

dosubot bot added size:L This PR changes 100-499 lines, ignoring generated files. bug Something isn't working labels Sep 3, 2025

roomote bot commented Sep 3, 2025

View reviewed changes

roomote bot mentioned this pull request Sep 3, 2025

Roo may call mcp tool that is known not to exist. #7631

Closed

hannesrudolph added the Issue/PR - Triage New issue. Needs quick review to confirm validity and assign labels. label Sep 3, 2025

daniel-lxs moved this from Triage to PR [Needs Prelim Review] in Roo Code Roadmap Sep 4, 2025

hannesrudolph added PR - Needs Preliminary Review and removed Issue/PR - Triage New issue. Needs quick review to confirm validity and assign labels. labels Sep 4, 2025

fix(mcp): fail fast on unknown server; add i18n keys/translations; ad…

326268a

…d tests

daniel-lxs moved this from PR [Needs Prelim Review] to PR [Needs Review] in Roo Code Roadmap Sep 4, 2025

daniel-lxs approved these changes Sep 4, 2025

View reviewed changes

dosubot bot added the lgtm This PR has been approved by a maintainer label Sep 4, 2025

hannesrudolph added PR - Needs Review and removed PR - Needs Preliminary Review labels Sep 4, 2025

mrubens reviewed Sep 4, 2025

View reviewed changes

ellipsis-dev bot reviewed Sep 4, 2025

View reviewed changes

fix: use translation for disabled tool error message

97945bd

- Replace hardcoded error message with t() translation function - Add toolDisabled translation key to all 17 locale files - Maintains proper placeholder variables for code integration

mrubens approved these changes Sep 4, 2025

View reviewed changes

mrubens merged commit 7935c94 into main Sep 4, 2025
9 checks passed

github-project-automation bot moved this from New to Done in Roo Code Roadmap Sep 4, 2025

github-project-automation bot moved this from PR [Needs Review] to Done in Roo Code Roadmap Sep 4, 2025

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

fix: validate MCP tool exists before execution #7632

fix: validate MCP tool exists before execution #7632

Uh oh!

roomote bot commented Sep 3, 2025 •

edited by ellipsis-dev bot

Loading

Uh oh!

roomote bot left a comment

Uh oh!

roomote bot Sep 3, 2025

Uh oh!

roomote bot Sep 3, 2025

Uh oh!

roomote bot Sep 3, 2025

Uh oh!

daniel-lxs left a comment

Uh oh!

mrubens Sep 4, 2025

Uh oh!

daniel-lxs Sep 4, 2025

Uh oh!

R-omk Sep 6, 2025

Uh oh!

ellipsis-dev bot Sep 4, 2025

Uh oh!

Uh oh!

	`Tool '${toolName}' on server '${serverName}' is disabled. Available enabled tools: ${enabledToolNames.length > 0 ? enabledToolNames.join(", ") : "No enabled tools available"}`,
	t('mcp:errors.toolDisabled', { toolName, serverName, enabledTools: enabledToolNames.length > 0 ? enabledToolNames.join(", ") : "No enabled tools available" }),

fix: validate MCP tool exists before execution #7632

fix: validate MCP tool exists before execution #7632

Uh oh!

Conversation

roomote bot commented Sep 3, 2025 • edited by ellipsis-dev bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Problem

Solution

Changes

Testing

Uh oh!

roomote bot left a comment

Choose a reason for hiding this comment

Uh oh!

roomote bot Sep 3, 2025

Choose a reason for hiding this comment

Uh oh!

roomote bot Sep 3, 2025

Choose a reason for hiding this comment

Uh oh!

roomote bot Sep 3, 2025

Choose a reason for hiding this comment

Uh oh!

daniel-lxs left a comment

Choose a reason for hiding this comment

Uh oh!

mrubens Sep 4, 2025

Choose a reason for hiding this comment

Uh oh!

daniel-lxs Sep 4, 2025

Choose a reason for hiding this comment

Uh oh!

R-omk Sep 6, 2025

Choose a reason for hiding this comment

Uh oh!

ellipsis-dev bot Sep 4, 2025

Choose a reason for hiding this comment

Uh oh!

Uh oh!

roomote bot commented Sep 3, 2025 •

edited by ellipsis-dev bot

Loading