`MISSING_TOOL_DESCRIPTION` false positive: Validator checks wrong property name for toolWorkflow, toolCode, and toolSerpApi nodes

[drbhatiasanjay]

GitHub Issue: MISSING_TOOL_DESCRIPTION False Positive for toolWorkflow, toolCode, and toolSerpApi

Bug Report for czlonkowski/n8n-mcp

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Issue Title

MISSING_TOOL_DESCRIPTION false positive: Validator checks wrong property name for toolWorkflow, toolCode, and toolSerpApi nodes

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Description

The AI tool validators in src/services/ai-tool-validators.ts always check for node.parameters.toolDescription, but n8n uses different property names for different tool types:

Tool Type	Actual n8n Property	Validator Checks	Result
toolHttpRequest	toolDescription	toolDescription	✅ Correct
toolWorkflow	description	toolDescription	❌ False positive
toolCode	description	toolDescription	❌ False positive
toolSerpApi	options.description	toolDescription	❌ False positive

This causes valid workflows with properly configured tool descriptions to fail validation with MISSING_TOOL_DESCRIPTION errors.

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Steps to Reproduce

1. Create a workflow with a toolWorkflow node (Call n8n Sub-Workflow Tool)
2. Configure the description field with a valid description (e.g., "Delete a content source permanently from the knowledge base")
3. Connect the tool to an AI Agent
4. Run n8n_validate_workflow on the workflow

Expected: Validation passes (description is present)
Actual: Error: Workflow Tool "X" has no toolDescription. Add one to help the LLM know when to use this tool.

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Evidence

n8n Node Schema (from get_node tool)

toolWorkflow uses description:

{
  "name": "description",
  "displayName": "Description",
  "type": "string",
  "path": "description"
}

toolHttpRequest uses toolDescription:

{
  "name": "toolDescription",
  "displayName": "Description",
  "type": "string",
  "path": "toolDescription"
}

toolCode uses description:

{
  "name": "description",
  "displayName": "Description",
  "type": "string",
  "path": "description"
}

Actual Workflow Data (with descriptions present)

// toolWorkflow node - has description but validator fails
{
  "name": "Add Content Source",
  "type": "@n8n/n8n-nodes-langchain.toolWorkflow",
  "parameters": {
    "workflowId": { "value": "0RDJJbYpXmJK5adO", "mode": "list" },
    "description": "Add a new content source to the knowledge base..."  // ✅ Present!
  }
}

// toolSerpApi node - has options.description but validator fails
{
  "name": "Google SerpAPI",
  "type": "@n8n/n8n-nodes-langchain.toolSerpApi",
  "parameters": {
    "options": {
      "description": "Search the web using Google to find additional resources..."  // ✅ Present!
    }
  }
}

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Root Cause

In src/services/ai-tool-validators.ts, all validators use the same check:

// Line ~57, ~213, ~237, ~273, ~323, etc.
if (!node.parameters.toolDescription) {
  issues.push({
    severity: 'error',
    ...
    code: 'MISSING_TOOL_DESCRIPTION'
  });
}

But n8n's actual node schemas use different property names depending on the tool type.

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Affected Validators

1. validateWorkflowTool() - Line ~303
2. validateCodeTool() - Line ~213
3. validateSerpApiTool() - Line ~357
4. validateVectorStoreTool() - Line ~237
5. validateAIAgentTool() - Line ~273
6. validateMCPClientTool() - Line ~323
7. validateWikipediaTool() - Line ~377
8. validateSearXngTool() - Line ~395

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Suggested Fix

Create a helper function to check all possible description locations:

/**
 * Get tool description from node, checking all possible property locations
 * Different n8n tool types store descriptions in different places
 */
function getToolDescription(node: WorkflowNode): string | undefined {
  return (
    node.parameters.toolDescription ||      // HTTP Request Tool, Vector Store Tool
    node.parameters.description ||          // Workflow Tool, Code Tool, AI Agent Tool
    node.parameters.options?.description    // SerpApi, Wikipedia, SearXNG
  );
}

Then update each validator:

// Before (wrong):
if (!node.parameters.toolDescription) {

// After (correct):
const description = getToolDescription(node);
if (!description) {

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Environment

• n8n-mcp version: 2.28.8
• n8n instance version: 1.121.3
• Node types affected: toolWorkflow, toolCode, toolSerpApi (and potentially others)

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Additional Context

This bug was discovered while validating the "Abhishek Basic Agentic5b" workflow which has 9 properly configured AI tools. 5 of them (all toolWorkflow and toolSerpApi nodes) incorrectly fail validation despite having valid descriptions.

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Labels

bug, validation, ai-tools