ExpressJS MCP

# Example 05: Dynamic Tool Management This example demonstrates how to dynamically add, remove, and update MCP tools at runtime without restarting the server. ## Features - **Add Tools**: Create new endpoints and expose them as MCP tools - **Remove Tools**: Disable tools without stopping the server - **Batch Operations**: Add/remove multiple tools at once - **Configuration Loading**: Load tools from configuration - **Tool Discovery**: Re-initialize MCP to discover changes ## Running the Example ```bash # Install dependencies pnpm install # Run the example pnpm tsx examples/05-dynamic-tools/server.ts ``` ## API Endpoints ### Add a Tool ```bash curl -X POST http://localhost:3005/admin/tools/add \ -H "Content-Type: application/json" \ -d '{ "path": "/api/dynamic/users", "method": "GET" }' ``` ### Remove a Tool ```bash curl -X DELETE http://localhost:3005/admin/tools/remove \ -H "Content-Type: application/json" \ -d '{ "path": "/api/dynamic/users", "method": "GET" }' ``` ### List All Tools ```bash curl http://localhost:3005/admin/tools/list ``` Response: ```json { "total": 10, "static": 2, "dynamic": 8, "tools": [ { "name": "GET_/health", "title": "GET /health", "isDynamic": false }, { "name": "GET_/api/dynamic/users", "title": "GET /api/dynamic/users", "isDynamic": true } ] } ``` ### Batch Operations ```bash curl -X POST http://localhost:3005/admin/tools/batch \ -H "Content-Type: application/json" \ -d '{ "operations": [ { "action": "add", "path": "/api/v3/products", "method": "GET" }, { "action": "add", "path": "/api/v3/products", "method": "POST" }, { "action": "remove", "path": "/api/v1/users", "method": "GET" } ] }' ``` ### Load Configuration ```bash curl -X POST http://localhost:3005/admin/tools/load-config \ -H "Content-Type: application/json" \ -d '{ "config": [ { "path": "/api/v2/products", "method": "GET" }, { "path": "/api/v2/products/:id", "method": "GET" }, { "path": "/api/v2/orders", "method": "GET" } ] }' ``` ## Use Cases ### Feature Flags Enable/disable features dynamically: ```javascript if (featureFlags.newApi) { await addTool("/api/v2/feature", "POST"); } ``` ### A/B Testing Different tools for different user groups: ```javascript const userGroup = getUserGroup(userId); if (userGroup === "beta") { await loadBetaTools(); } ``` ### Plugin System Load tools from plugins: ```javascript for (const plugin of enabledPlugins) { await loadPluginTools(plugin); } ``` ### API Versioning Manage multiple API versions: ```javascript // Enable v2 endpoints await loadConfig(v2Config); // Disable v1 endpoints await removeTools(v1Endpoints); ``` ## Implementation Details ### Dynamic Route Registration Routes are added to Express at runtime: ```typescript app[method.toLowerCase()](path, handler); dynamicRoutes.set(routeKey, { path, method, handler }); await mcp.init(); // Re-discover routes ``` ### Tool Discovery MCP re-initializes to discover new routes: ```typescript await mcp.init(); // Introspects Express router again ``` ### Limitations 1. **Route Removal**: Express doesn't provide a clean API to remove routes 2. **Performance**: Re-initialization has overhead for large route sets 3. **Persistence**: Dynamic routes are lost on restart ## Best Practices 1. **Validation**: Validate route paths and methods 2. **Conflict Detection**: Check for existing routes 3. **Error Handling**: Handle registration failures gracefully 4. **Persistence**: Store dynamic routes in database 5. **Security**: Authenticate admin endpoints ## Testing Dynamic Tools 1. Start the server 2. Load example configuration 3. List tools to see both static and dynamic 4. Invoke a dynamic tool via MCP 5. Remove a tool and verify it's gone ```bash # Load config curl -X POST http://localhost:3005/admin/tools/load-config -H "Content-Type: application/json" -d '{}' # List tools curl http://localhost:3005/admin/tools/list | jq '.tools | length' # Invoke dynamic tool curl -X POST http://localhost:3005/mcp/invoke \ -H "Content-Type: application/json" \ -d '{"toolName": "GET_/api/v2/products", "args": {}}' ``` ## Next Steps - See [Example 06](../06-custom-router) for custom MCP routing - See [Example 08](../08-auth-token) for authentication