fix: recognize dynamic AI Tool nodes in validator (Issue #522) (#526)

When n8n connects any node to an AI Agent's tool slot, it creates a
dynamic Tool variant at runtime (e.g., googleDrive → googleDriveTool).
These don't exist in npm packages, causing false "unknown node type"
errors.

Added validation-time inference: when a *Tool node type is not found,
check if the base node exists. If yes, treat as valid with warning.

Changes:
- workflow-validator.ts: Add INFERRED_TOOL_VARIANT logic
- node-similarity-service.ts: Add 98% confidence for valid Tool variants
- Added 7 unit tests for inferred tool variant functionality

Fixes #522

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Romuald Członkowski <romualdczlonkowski@MacBook-Pro-Romuald.local>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

src/services/workflow-validator.ts

@@ -398,7 +398,39 @@ export class WorkflowValidator {
         const normalizedType = NodeTypeNormalizer.normalizeToFullForm(node.type);
 
         // Get node definition using normalized type (needed for typeVersion validation)
-        const nodeInfo = this.nodeRepository.getNode(normalizedType);
+        let nodeInfo = this.nodeRepository.getNode(normalizedType);
+
+        // Check if this is a dynamic Tool variant (e.g., googleDriveTool, googleSheetsTool)
+        // n8n creates these at runtime when ANY node is used in an AI Agent's tool slot,
+        // but they don't exist in npm packages. We infer validity if the base node exists.
+        // See: https://github.com/czlonkowski/n8n-mcp/issues/522
+        if (!nodeInfo && ToolVariantGenerator.isToolVariantNodeType(normalizedType)) {
+          const baseNodeType = ToolVariantGenerator.getBaseNodeType(normalizedType);
+          if (baseNodeType) {
+            const baseNodeInfo = this.nodeRepository.getNode(baseNodeType);
+            if (baseNodeInfo) {
+              // Valid inferred tool variant - base node exists
+              result.warnings.push({
+                type: 'warning',
+                nodeId: node.id,
+                nodeName: node.name,
+                message: `Node type "${node.type}" is inferred as a dynamic AI Tool variant of "${baseNodeType}". ` +
+                  `This Tool variant is created by n8n at runtime when connecting "${baseNodeInfo.displayName}" to an AI Agent.`,
+                code: 'INFERRED_TOOL_VARIANT'
+              });
+
+              // Create synthetic nodeInfo for validation continuity
+              nodeInfo = {
+                ...baseNodeInfo,
+                nodeType: normalizedType,
+                displayName: `${baseNodeInfo.displayName} Tool`,
+                isToolVariant: true,
+                toolVariantOf: baseNodeType,
+                isInferred: true
+              };
+            }
+          }
+        }
 
         if (!nodeInfo) {
 
@@ -494,6 +526,13 @@ export class WorkflowValidator {
           continue;
         }
 
+        // Skip PARAMETER validation for inferred tool variants (Issue #522)
+        // They have a different property structure (toolDescription added at runtime)
+        // that doesn't match the base node's schema. TypeVersion validation above still runs.
+        if ((nodeInfo as any).isInferred) {
+          continue;
+        }
+
         // Validate node configuration
         // Add @version to parameters for displayOptions evaluation (supports _cnd operators)
         const paramsWithVersion = {