NestJS MCP Server Module

What is NestJS MCP Server Module?

It is a NestJS module that simplifies building an MCP (Model Context Protocol) server with Server-Sent Events (SSE) transport. It automatically discovers and registers tools and resources defined with decorators, and integrates Zod-based request validation, progress notifications, and NestJS guard authentication.

How to use NestJS MCP Server Module?

Install the package and its peer dependencies (npm install @rekog/mcp-nest @modelcontextprotocol/sdk zod), then import McpModule.forRoot in your root module with a server name and version. Decorate service methods with @Tool and @Resource to register tools and resources. Optionally apply NestJS guards for endpoint authentication.

Key features of NestJS MCP Server Module

• SSE transport for streaming tool execution and resource access
• Automatic tool and resource discovery via decorators
• Zod-based request validation for tool parameters
• Progress notifications during long-running operations
• Guard-based authentication on /sse and /messages endpoints

Use cases of NestJS MCP Server Module

• Building a secure MCP server within an existing NestJS application
• Streaming tool calls with real‑time progress updates to AI clients
• Exposing dynamic resources via URI templates with guard‑protected access
• Using MCP tool and resource discovery without manual route registration

FAQ from NestJS MCP Server Module

What is the difference between using this module and the raw MCP SDK?

This module provides NestJS‑native decorators (@Tool, @Resource), automatic discovery, and guard integration, so you don’t have to manually wire tool/resource handlers or handle SSE connections.

What are the runtime dependencies?

Node.js, NestJS (any version supporting dynamic modules), @modelcontextprotocol/sdk, and zod. The module itself is @rekog/mcp-nest.

Which transport does the server use?

Server-Sent Events (SSE) on the GET /sse endpoint, with POST /messages for receiving client responses.

How can I secure the MCP endpoints?

Pass standard NestJS guards to McpModule.forRoot in the guards array. Those guards are applied to both the SSE and messages endpoints. You can also exclude /sse and /messages from a global prefix using { exclude: ['sse', 'messages'] }.

Does the module support resource templates?

Yes. Use the @Resource decorator with a URI template (e.g., mcp://hello-world/{userName}) – the module captures the dynamic parameters and passes them to the handler.