NestJS MCP Server Module

A NestJS module to effortlessly expose tools, resources, and prompts for AI, from your NestJS applications using the Model Context Protocol (MCP).

With @rekog/mcp-nest you define tools, resources, and prompts in a way that's familiar in NestJS and leverage the full power of dependency injection to utilize your existing codebase in building complex enterprise ready MCP servers.

Features

• 🚀 Multi-Transport Support: HTTP+SSE, Streamable HTTP, and STDIO
• 🔧 Tools: Expose NestJS methods as MCP tools with automatic discovery and Zod validation
  • 🛠️ Elicitation: Interactive tool calls with user input elicitation
  • 🌐 HTTP Request Access: Full access to request context within MCP handlers
  • 🔐 Per-Tool Authorization: Implement fine-grained authorization for tools
• 📁 Resources: Serve content and data through MCP resource system
• 📚 Resource Templates: Dynamic resources with parameterized URIs
• 💬 Prompts: Define reusable prompt templates for AI interactions
• 🔐 Guard-based Authentication: Guard-based security with OAuth support
• 🏠 Built-in Authorization Server — Using the built-in Authorization Server for easy setups. (Beta)
• 🌐 External Authorization Server — Securing your MCP server with an external authorization server (Keycloak, Auth0, etc).
• 💉 Dependency Injection: Leverage NestJS DI system throughout MCP components

Are you interested to build ChatGPT widgets (with the OpenAI SDK)? Find out how to do that with @rekog/MCP-Nest in this repository MCP-Nest-Samples/pizzaz-openai-apps-sdk

Installation

npm install @rekog/mcp-nest @modelcontextprotocol/sdk zod@^4

Optional dependencies

If you use the built-in authorization server with the TypeORM store, install the following optional peer dependencies:

npm install @nestjs/typeorm typeorm

Quick Start

// app.module.ts
import { Module } from '@nestjs/common';
import { McpModule } from '@rekog/mcp-nest';
import { GreetingTool } from './greeting.tool';

@Module({
  imports: [
    McpModule.forRoot({
      name: 'my-mcp-server',
      version: '1.0.0',
    }),
  ],
  providers: [GreetingTool],
})
export class AppModule {}

// greeting.tool.ts
import { Injectable } from '@nestjs/common';
import { Tool, Context } from '@rekog/mcp-nest';
import { z } from 'zod';

@Injectable()
export class GreetingTool {
  @Tool({
    name: 'greeting-tool',
    description: 'Returns a greeting with progress updates',
    parameters: z.object({
      name: z.string().default('World'),
    }),
  })
  async sayHello({ name }, context: Context) {
    await context.reportProgress({ progress: 50, total: 100 });
    return `Hello, ${name}!`;
  }
}

Documentation

• Tools Guide - Define and expose NestJS methods as MCP tools
• Discovery and Registration of Tools - Automatic discovery and manual registration of tools
• Dynamic Tools Guide - Register tools programmatically at runtime
• Resources Guide - Serve static and dynamic content
• Resource Templates Guide - Create parameterized resources
• Prompts Guide - Build reusable prompt templates
• Built-in Authorization Server - Secure your MCP server with built-in OAuth
• External Authorization Server - Securing your MCP server with an external authorization server (Keycloak, Auth0, etc)
• Server examples - MCP servers examples (Streamable HTTP, HTTP, and STDIO) and with Fastify support

Playground

The playground directory contains working examples for all features. Refer to playground/README.md for details.