feat: add version info to health check and fix healthz endpoint

- Fixed health check to use correct /healthz endpoint instead of /health
- Added MCP version (mcpVersion) and supported n8n version (supportedN8nVersion) to health check response
- Added versionNote field with instructions for AI agents about manual version verification
- n8n API limitation: instance version cannot be determined automatically
- Updated axios usage for healthz endpoint access with proper error handling

src/mcp/handlers-n8n-manager.ts

@@ -758,6 +758,11 @@ export async function handleHealthCheck(): Promise<McpToolResponse> {
     const client = ensureApiConfigured();
     const health = await client.healthCheck();
     
+    // Get MCP version from package.json
+    const packageJson = require('../../package.json');
+    const mcpVersion = packageJson.version;
+    const supportedN8nVersion = packageJson.dependencies?.n8n?.replace(/[^0-9.]/g, '');
+    
     return {
       success: true,
       data: {
@@ -765,7 +770,10 @@ export async function handleHealthCheck(): Promise<McpToolResponse> {
         instanceId: health.instanceId,
         n8nVersion: health.n8nVersion,
         features: health.features,
-        apiUrl: getN8nApiConfig()?.baseUrl
+        apiUrl: getN8nApiConfig()?.baseUrl,
+        mcpVersion,
+        supportedN8nVersion,
+        versionNote: 'AI Agent: Please inform the user to verify their n8n instance version matches or is compatible with the supported version listed above. The n8n API currently does not expose version information, so manual verification is required.'
       }
     };
   } catch (error) {

src/services/n8n-api-client.ts

@@ -87,17 +87,32 @@ export class N8nApiClient {
   // Health check to verify API connectivity
   async healthCheck(): Promise<HealthCheckResponse> {
     try {
-      // First try the health endpoint
-      const response = await this.client.get('/health');
-      return response.data;
+      // Try the standard healthz endpoint (available on all n8n instances)
+      const baseUrl = this.client.defaults.baseURL || '';
+      const healthzUrl = baseUrl.replace(/\/api\/v\d+\/?$/, '') + '/healthz';
+      
+      const response = await axios.get(healthzUrl, {
+        timeout: 5000,
+        validateStatus: (status) => status < 500
+      });
+      
+      if (response.status === 200 && response.data?.status === 'ok') {
+        return { 
+          status: 'ok',
+          features: {} // Features detection would require additional endpoints
+        };
+      }
+      
+      // If healthz doesn't work, fall back to API check
+      throw new Error('healthz endpoint not available');
     } catch (error) {
-      // If health endpoint doesn't exist, try listing workflows with limit 1
+      // If healthz endpoint doesn't exist, try listing workflows with limit 1
       // This is a fallback for older n8n versions
       try {
         await this.client.get('/workflows', { params: { limit: 1 } });
         return { 
           status: 'ok',
-          features: {} // We can't determine features without proper health endpoint
+          features: {}
         };
       } catch (fallbackError) {
         throw handleN8nApiError(fallbackError);