rahosung/MCP_Server
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A NestJS module for creating an MCP (Model Context Protocol) server with Server-Sent Events (SSE) transport.
NestJS MCP Server Module
A NestJS module for creating an MCP (Model Context Protocol) server with Server-Sent Events (SSE) transport.
Features
- 🚀 SSE Transport for streaming and tool execution
- 🔍 Automatic
toolandresourcediscovery and registration - 💯 Zod-based request validation
- 📊 Progress notifications
- 🔒 Guard-based authentication
Installation
npm install @rekog/mcp-nest @modelcontextprotocol/sdk zod
Quick Start
1. Import Module
// 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 {}
2. Define Tools and Resource
// greeting.tool.ts
import { Injectable } from '@nestjs/common';
import { Tool, Context } from '@rekog/mcp-nest';
import { z } from 'zod';
import { Progress } from '@modelcontextprotocol/sdk/types';
@Injectable()
export class GreetingTool {
constructor() {}
@Tool({
name: 'hello-world',
description:
'Returns a greeting and simulates a long operation with progress updates',
parameters: z.object({
name: z.string().default('World'),
}),
})
async sayHello({ name }, context: Context) {
const greeting = `Hello, ${name}!`;
const totalSteps = 5;
for (let i = 0; i < totalSteps; i++) {
await new Promise((resolve) => setTimeout(resolve, 500));
// Send a progress update.
await context.reportProgress({
progress: (i + 1) * 20,
total: 100,
} as Progress);
}
return {
content: [{ type: 'text', text: greeting }],
};
}
@Resource({
uri: 'mcp://hello-world/{userName}',
name: 'Hello World',
description: 'A simple greeting resource',
mimeType: 'text/plain',
})
// Different from the SDK, we put the parameters and URI in the same object.
async getCurrentSchema({ uri, userName }) {
return {
content: [
{
uri,
text: `User is ${userName}`,
mimeType: 'text/plain',
},
],
};
}
}
You are done!
API Endpoints
GET /sse: SSE connection endpoint (Protected by guards if configured)POST /messages: Tool execution endpoint (Protected by guards if configured)
Tips
It's possible to use the module with global prefix, but the recommended way is to exclude those endpoints with:
app.setGlobalPrefix('/api', { exclude: ['sse', 'messages'] });
Authentication
You can secure your MCP endpoints using standard NestJS Guards.
1. Create a Guard
Implement the CanActivate interface. The guard should handle request validation (e.g., checking JWTs, API keys) and optionally attach user information to the request object.
Nothing special, check the NestJS documentation for more details.
2. Apply the Guard
Pass your guard(s) to the McpModule.forRoot configuration. The guard(s) will be applied to both the /sse and /messages endpoints.
// app.module.ts
import { Module } from '@nestjs/common';
import { McpModule } from '@rekog/mcp-nest';
import { GreetingTool } from './greeting.tool';
import { AuthGuard } from './auth.guard';
@Module({
imports: [
McpModule.forRoot({
name: 'my-mcp-server',
version: '1.0.0',
guards: [AuthGuard], // Apply the guard here
}),
],
providers: [GreetingTool, AuthGuard], // Ensure the Guard is also provided
})
export class AppModule {}
That's it! The rest is the same as NestJS Guards.
