feat: implement Phase 8 integration tests for system tools

Implement comprehensive integration tests for 3 system tool handlers:
- handleHealthCheck (3 tests): API connectivity, version checking, feature availability
- handleListAvailableTools (7 tests): Tool discovery by category, configuration status, API limitations
- handleDiagnostic (9 tests): Environment checks, API status, tools availability, verbose mode

All 19 tests passing against real n8n instance.

Coverage:
- Health check: API availability verification, version information, feature discovery
- Tool listing: All categories (Workflow Management, Execution Management, System), configuration details
- Diagnostics: Environment variables, API connectivity, tool availability, troubleshooting steps, verbose debug mode

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

Co-Authored-By: Claude <noreply@anthropic.com>

tests/integration/n8n-api/system/list-tools.test.ts

@@ -0,0 +1,207 @@
+/**
+ * Integration Tests: handleListAvailableTools
+ *
+ * Tests tool listing functionality.
+ * Covers tool discovery and configuration status.
+ */
+
+import { describe, it, expect, beforeEach } from 'vitest';
+import { createMcpContext } from '../utils/mcp-context';
+import { InstanceContext } from '../../../../src/types/instance-context';
+import { handleListAvailableTools } from '../../../../src/mcp/handlers-n8n-manager';
+
+describe('Integration: handleListAvailableTools', () => {
+  let mcpContext: InstanceContext;
+
+  beforeEach(() => {
+    mcpContext = createMcpContext();
+  });
+
+  // ======================================================================
+  // List All Tools
+  // ======================================================================
+
+  describe('Tool Listing', () => {
+    it('should list all available tools organized by category', async () => {
+      const response = await handleListAvailableTools(mcpContext);
+
+      expect(response.success).toBe(true);
+      expect(response.data).toBeDefined();
+
+      const data = response.data as any;
+
+      // Verify tools array exists
+      expect(data).toHaveProperty('tools');
+      expect(Array.isArray(data.tools)).toBe(true);
+      expect(data.tools.length).toBeGreaterThan(0);
+
+      // Verify tool categories
+      const categories = data.tools.map((cat: any) => cat.category);
+      expect(categories).toContain('Workflow Management');
+      expect(categories).toContain('Execution Management');
+      expect(categories).toContain('System');
+
+      // Verify each category has tools
+      data.tools.forEach((category: any) => {
+        expect(category).toHaveProperty('category');
+        expect(category).toHaveProperty('tools');
+        expect(Array.isArray(category.tools)).toBe(true);
+        expect(category.tools.length).toBeGreaterThan(0);
+
+        // Verify each tool has required fields
+        category.tools.forEach((tool: any) => {
+          expect(tool).toHaveProperty('name');
+          expect(tool).toHaveProperty('description');
+          expect(typeof tool.name).toBe('string');
+          expect(typeof tool.description).toBe('string');
+        });
+      });
+    });
+
+    it('should include API configuration status', async () => {
+      const response = await handleListAvailableTools(mcpContext);
+
+      expect(response.success).toBe(true);
+      const data = response.data as any;
+
+      // Verify configuration status
+      expect(data).toHaveProperty('apiConfigured');
+      expect(typeof data.apiConfigured).toBe('boolean');
+
+      // Since tests run with API configured, should be true
+      expect(data.apiConfigured).toBe(true);
+
+      // Verify configuration details are present when configured
+      if (data.apiConfigured) {
+        expect(data).toHaveProperty('configuration');
+        expect(data.configuration).toBeDefined();
+        expect(data.configuration).toHaveProperty('apiUrl');
+        expect(data.configuration).toHaveProperty('timeout');
+        expect(data.configuration).toHaveProperty('maxRetries');
+      }
+    });
+
+    it('should include API limitations information', async () => {
+      const response = await handleListAvailableTools(mcpContext);
+
+      expect(response.success).toBe(true);
+      const data = response.data as any;
+
+      // Verify limitations are documented
+      expect(data).toHaveProperty('limitations');
+      expect(Array.isArray(data.limitations)).toBe(true);
+      expect(data.limitations.length).toBeGreaterThan(0);
+
+      // Verify limitations are informative strings
+      data.limitations.forEach((limitation: string) => {
+        expect(typeof limitation).toBe('string');
+        expect(limitation.length).toBeGreaterThan(0);
+      });
+
+      // Common known limitations
+      const limitationsText = data.limitations.join(' ');
+      expect(limitationsText).toContain('Cannot activate');
+      expect(limitationsText).toContain('Cannot execute workflows directly');
+    });
+  });
+
+  // ======================================================================
+  // Workflow Management Tools
+  // ======================================================================
+
+  describe('Workflow Management Tools', () => {
+    it('should include all workflow management tools', async () => {
+      const response = await handleListAvailableTools(mcpContext);
+      const data = response.data as any;
+
+      const workflowCategory = data.tools.find((cat: any) => cat.category === 'Workflow Management');
+      expect(workflowCategory).toBeDefined();
+
+      const toolNames = workflowCategory.tools.map((t: any) => t.name);
+
+      // Core workflow tools
+      expect(toolNames).toContain('n8n_create_workflow');
+      expect(toolNames).toContain('n8n_get_workflow');
+      expect(toolNames).toContain('n8n_update_workflow');
+      expect(toolNames).toContain('n8n_delete_workflow');
+      expect(toolNames).toContain('n8n_list_workflows');
+
+      // Enhanced workflow tools
+      expect(toolNames).toContain('n8n_get_workflow_details');
+      expect(toolNames).toContain('n8n_get_workflow_structure');
+      expect(toolNames).toContain('n8n_get_workflow_minimal');
+      expect(toolNames).toContain('n8n_validate_workflow');
+      expect(toolNames).toContain('n8n_autofix_workflow');
+    });
+  });
+
+  // ======================================================================
+  // Execution Management Tools
+  // ======================================================================
+
+  describe('Execution Management Tools', () => {
+    it('should include all execution management tools', async () => {
+      const response = await handleListAvailableTools(mcpContext);
+      const data = response.data as any;
+
+      const executionCategory = data.tools.find((cat: any) => cat.category === 'Execution Management');
+      expect(executionCategory).toBeDefined();
+
+      const toolNames = executionCategory.tools.map((t: any) => t.name);
+
+      expect(toolNames).toContain('n8n_trigger_webhook_workflow');
+      expect(toolNames).toContain('n8n_get_execution');
+      expect(toolNames).toContain('n8n_list_executions');
+      expect(toolNames).toContain('n8n_delete_execution');
+    });
+  });
+
+  // ======================================================================
+  // System Tools
+  // ======================================================================
+
+  describe('System Tools', () => {
+    it('should include system tools', async () => {
+      const response = await handleListAvailableTools(mcpContext);
+      const data = response.data as any;
+
+      const systemCategory = data.tools.find((cat: any) => cat.category === 'System');
+      expect(systemCategory).toBeDefined();
+
+      const toolNames = systemCategory.tools.map((t: any) => t.name);
+
+      expect(toolNames).toContain('n8n_health_check');
+      expect(toolNames).toContain('n8n_list_available_tools');
+    });
+  });
+
+  // ======================================================================
+  // Response Format Verification
+  // ======================================================================
+
+  describe('Response Format', () => {
+    it('should return complete tool list response structure', async () => {
+      const response = await handleListAvailableTools(mcpContext);
+
+      expect(response.success).toBe(true);
+      expect(response.data).toBeDefined();
+
+      const data = response.data as any;
+
+      // Verify all required fields
+      expect(data).toHaveProperty('tools');
+      expect(data).toHaveProperty('apiConfigured');
+      expect(data).toHaveProperty('limitations');
+
+      // Verify optional configuration field
+      if (data.apiConfigured) {
+        expect(data).toHaveProperty('configuration');
+      }
+
+      // Verify data types
+      expect(Array.isArray(data.tools)).toBe(true);
+      expect(typeof data.apiConfigured).toBe('boolean');
+      expect(Array.isArray(data.limitations)).toBe(true);
+    });
+  });
+});