diff --git a/tests/integration/n8n-api/system/diagnostic.test.ts b/tests/integration/n8n-api/system/diagnostic.test.ts
new file mode 100644
index 0000000..986447d
--- /dev/null
+++ b/tests/integration/n8n-api/system/diagnostic.test.ts
@@ -0,0 +1,268 @@
+/**
+ * Integration Tests: handleDiagnostic
+ *
+ * Tests system diagnostic functionality.
+ * Covers environment checks, API status, and verbose mode.
+ */
+
+import { describe, it, expect, beforeEach } from 'vitest';
+import { createMcpContext } from '../utils/mcp-context';
+import { InstanceContext } from '../../../../src/types/instance-context';
+import { handleDiagnostic } from '../../../../src/mcp/handlers-n8n-manager';
+
+describe('Integration: handleDiagnostic', () => {
+  let mcpContext: InstanceContext;
+
+  beforeEach(() => {
+    mcpContext = createMcpContext();
+  });
+
+  // ======================================================================
+  // Basic Diagnostic
+  // ======================================================================
+
+  describe('Basic Diagnostic', () => {
+    it('should run basic diagnostic check', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: {} } },
+        mcpContext
+      );
+
+      expect(response.success).toBe(true);
+      expect(response.data).toBeDefined();
+
+      const data = response.data as any;
+
+      // Verify core diagnostic fields
+      expect(data).toHaveProperty('timestamp');
+      expect(data).toHaveProperty('environment');
+      expect(data).toHaveProperty('apiConfiguration');
+      expect(data).toHaveProperty('toolsAvailability');
+      expect(data).toHaveProperty('troubleshooting');
+
+      // Verify timestamp format
+      expect(typeof data.timestamp).toBe('string');
+      const timestamp = new Date(data.timestamp);
+      expect(timestamp.toString()).not.toBe('Invalid Date');
+    });
+
+    it('should include environment variables', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: {} } },
+        mcpContext
+      );
+
+      const data = response.data as any;
+
+      expect(data.environment).toBeDefined();
+      expect(data.environment).toHaveProperty('N8N_API_URL');
+      expect(data.environment).toHaveProperty('N8N_API_KEY');
+      expect(data.environment).toHaveProperty('NODE_ENV');
+      expect(data.environment).toHaveProperty('MCP_MODE');
+
+      // API key should be masked
+      if (data.environment.N8N_API_KEY) {
+        expect(data.environment.N8N_API_KEY).toBe('***configured***');
+      }
+    });
+
+    it('should check API configuration and connectivity', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: {} } },
+        mcpContext
+      );
+
+      const data = response.data as any;
+
+      expect(data.apiConfiguration).toBeDefined();
+      expect(data.apiConfiguration).toHaveProperty('configured');
+      expect(data.apiConfiguration).toHaveProperty('status');
+
+      // In test environment, API should be configured
+      expect(data.apiConfiguration.configured).toBe(true);
+
+      // Verify API status
+      const status = data.apiConfiguration.status;
+      expect(status).toHaveProperty('configured');
+      expect(status).toHaveProperty('connected');
+
+      // Should successfully connect to n8n API
+      expect(status.connected).toBe(true);
+
+      // If connected, should have version info
+      if (status.connected) {
+        expect(status).toHaveProperty('version');
+      }
+
+      // Config details should be present when configured
+      if (data.apiConfiguration.configured) {
+        expect(data.apiConfiguration).toHaveProperty('config');
+        expect(data.apiConfiguration.config).toHaveProperty('baseUrl');
+        expect(data.apiConfiguration.config).toHaveProperty('timeout');
+        expect(data.apiConfiguration.config).toHaveProperty('maxRetries');
+      }
+    });
+
+    it('should report tools availability', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: {} } },
+        mcpContext
+      );
+
+      const data = response.data as any;
+
+      expect(data.toolsAvailability).toBeDefined();
+      expect(data.toolsAvailability).toHaveProperty('documentationTools');
+      expect(data.toolsAvailability).toHaveProperty('managementTools');
+      expect(data.toolsAvailability).toHaveProperty('totalAvailable');
+
+      // Documentation tools should always be available
+      const docTools = data.toolsAvailability.documentationTools;
+      expect(docTools.count).toBeGreaterThan(0);
+      expect(docTools.enabled).toBe(true);
+      expect(docTools.description).toBeDefined();
+
+      // Management tools should be available when API configured
+      const mgmtTools = data.toolsAvailability.managementTools;
+      expect(mgmtTools).toHaveProperty('count');
+      expect(mgmtTools).toHaveProperty('enabled');
+      expect(mgmtTools).toHaveProperty('description');
+
+      // In test environment, management tools should be enabled
+      expect(mgmtTools.enabled).toBe(true);
+      expect(mgmtTools.count).toBeGreaterThan(0);
+
+      // Total should be sum of both
+      expect(data.toolsAvailability.totalAvailable).toBe(
+        docTools.count + mgmtTools.count
+      );
+    });
+
+    it('should include troubleshooting information', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: {} } },
+        mcpContext
+      );
+
+      const data = response.data as any;
+
+      expect(data.troubleshooting).toBeDefined();
+      expect(data.troubleshooting).toHaveProperty('steps');
+      expect(data.troubleshooting).toHaveProperty('documentation');
+
+      // Troubleshooting steps should be an array
+      expect(Array.isArray(data.troubleshooting.steps)).toBe(true);
+      expect(data.troubleshooting.steps.length).toBeGreaterThan(0);
+
+      // Documentation link should be present
+      expect(typeof data.troubleshooting.documentation).toBe('string');
+      expect(data.troubleshooting.documentation).toContain('https://');
+    });
+  });
+
+  // ======================================================================
+  // Verbose Mode
+  // ======================================================================
+
+  describe('Verbose Mode', () => {
+    it('should include additional debug info in verbose mode', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: { verbose: true } } },
+        mcpContext
+      );
+
+      expect(response.success).toBe(true);
+      const data = response.data as any;
+
+      // Verbose mode should add debug section
+      expect(data).toHaveProperty('debug');
+      expect(data.debug).toBeDefined();
+
+      // Verify debug information
+      expect(data.debug).toHaveProperty('processEnv');
+      expect(data.debug).toHaveProperty('nodeVersion');
+      expect(data.debug).toHaveProperty('platform');
+      expect(data.debug).toHaveProperty('workingDirectory');
+
+      // Process env should list relevant environment variables
+      expect(Array.isArray(data.debug.processEnv)).toBe(true);
+
+      // Node version should be a string
+      expect(typeof data.debug.nodeVersion).toBe('string');
+      expect(data.debug.nodeVersion).toMatch(/^v\d+\.\d+\.\d+/);
+
+      // Platform should be a string (linux, darwin, win32, etc.)
+      expect(typeof data.debug.platform).toBe('string');
+      expect(data.debug.platform.length).toBeGreaterThan(0);
+
+      // Working directory should be a path
+      expect(typeof data.debug.workingDirectory).toBe('string');
+      expect(data.debug.workingDirectory.length).toBeGreaterThan(0);
+    });
+
+    it('should not include debug info when verbose is false', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: { verbose: false } } },
+        mcpContext
+      );
+
+      expect(response.success).toBe(true);
+      const data = response.data as any;
+
+      // Debug section should not be present
+      expect(data.debug).toBeUndefined();
+    });
+
+    it('should not include debug info by default', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: {} } },
+        mcpContext
+      );
+
+      expect(response.success).toBe(true);
+      const data = response.data as any;
+
+      // Debug section should not be present when verbose not specified
+      expect(data.debug).toBeUndefined();
+    });
+  });
+
+  // ======================================================================
+  // Response Format Verification
+  // ======================================================================
+
+  describe('Response Format', () => {
+    it('should return complete diagnostic response structure', async () => {
+      const response = await handleDiagnostic(
+        { params: { arguments: {} } },
+        mcpContext
+      );
+
+      expect(response.success).toBe(true);
+      expect(response.data).toBeDefined();
+
+      const data = response.data as any;
+
+      // Verify all required fields
+      const requiredFields = [
+        'timestamp',
+        'environment',
+        'apiConfiguration',
+        'toolsAvailability',
+        'troubleshooting'
+      ];
+
+      requiredFields.forEach(field => {
+        expect(data).toHaveProperty(field);
+        expect(data[field]).toBeDefined();
+      });
+
+      // Verify data types
+      expect(typeof data.timestamp).toBe('string');
+      expect(typeof data.environment).toBe('object');
+      expect(typeof data.apiConfiguration).toBe('object');
+      expect(typeof data.toolsAvailability).toBe('object');
+      expect(typeof data.troubleshooting).toBe('object');
+    });
+  });
+});
diff --git a/tests/integration/n8n-api/system/health-check.test.ts b/tests/integration/n8n-api/system/health-check.test.ts
new file mode 100644
index 0000000..f8d460f
--- /dev/null
+++ b/tests/integration/n8n-api/system/health-check.test.ts
@@ -0,0 +1,109 @@
+/**
+ * Integration Tests: handleHealthCheck
+ *
+ * Tests API health check against a real n8n instance.
+ * Covers connectivity verification and feature availability.
+ */
+
+import { describe, it, expect, beforeEach } from 'vitest';
+import { createMcpContext } from '../utils/mcp-context';
+import { InstanceContext } from '../../../../src/types/instance-context';
+import { handleHealthCheck } from '../../../../src/mcp/handlers-n8n-manager';
+
+describe('Integration: handleHealthCheck', () => {
+  let mcpContext: InstanceContext;
+
+  beforeEach(() => {
+    mcpContext = createMcpContext();
+  });
+
+  // ======================================================================
+  // Successful Health Check
+  // ======================================================================
+
+  describe('API Available', () => {
+    it('should successfully check n8n API health', async () => {
+      const response = await handleHealthCheck(mcpContext);
+
+      expect(response.success).toBe(true);
+      expect(response.data).toBeDefined();
+
+      const data = response.data as any;
+
+      // Verify required fields
+      expect(data).toHaveProperty('status');
+      expect(data).toHaveProperty('apiUrl');
+      expect(data).toHaveProperty('mcpVersion');
+
+      // Status should be a string (e.g., "ok", "healthy")
+      if (data.status) {
+        expect(typeof data.status).toBe('string');
+      }
+
+      // API URL should match configuration
+      expect(data.apiUrl).toBeDefined();
+      expect(typeof data.apiUrl).toBe('string');
+
+      // MCP version should be defined
+      expect(data.mcpVersion).toBeDefined();
+      expect(typeof data.mcpVersion).toBe('string');
+    });
+
+    it('should include feature availability information', async () => {
+      const response = await handleHealthCheck(mcpContext);
+
+      expect(response.success).toBe(true);
+      const data = response.data as any;
+
+      // Check for feature information
+      // Note: Features may vary by n8n instance configuration
+      if (data.features) {
+        expect(typeof data.features).toBe('object');
+      }
+
+      // Check for version information
+      if (data.n8nVersion) {
+        expect(typeof data.n8nVersion).toBe('string');
+      }
+
+      if (data.supportedN8nVersion) {
+        expect(typeof data.supportedN8nVersion).toBe('string');
+      }
+
+      // Should include version note for AI agents
+      if (data.versionNote) {
+        expect(typeof data.versionNote).toBe('string');
+        expect(data.versionNote).toContain('version');
+      }
+    });
+  });
+
+  // ======================================================================
+  // Response Format Verification
+  // ======================================================================
+
+  describe('Response Format', () => {
+    it('should return complete health check response structure', async () => {
+      const response = await handleHealthCheck(mcpContext);
+
+      expect(response.success).toBe(true);
+      expect(response.data).toBeDefined();
+
+      const data = response.data as any;
+
+      // Verify all expected fields are present
+      const expectedFields = ['status', 'apiUrl', 'mcpVersion'];
+      expectedFields.forEach(field => {
+        expect(data).toHaveProperty(field);
+      });
+
+      // Optional fields that may be present
+      const optionalFields = ['instanceId', 'n8nVersion', 'features', 'supportedN8nVersion', 'versionNote'];
+      optionalFields.forEach(field => {
+        if (data[field] !== undefined) {
+          expect(data[field]).not.toBeNull();
+        }
+      });
+    });
+  });
+});
diff --git a/tests/integration/n8n-api/system/list-tools.test.ts b/tests/integration/n8n-api/system/list-tools.test.ts
new file mode 100644
index 0000000..1e37726
--- /dev/null
+++ b/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);
+    });
+  });
+});