@nest-mcp/gateway

NestJS module for aggregating multiple upstream MCP servers behind a single unified endpoint, with routing, caching, policies, and transforms.

Installation

npm install @nest-mcp/gateway @modelcontextprotocol/sdk zod@^4
npm install @nestjs/common @nestjs/core reflect-metadata rxjs

Quick start

// app.module.ts
import { Module } from '@nestjs/common';
import { McpGatewayModule } from '@nest-mcp/gateway';
import { McpTransportType } from '@nest-mcp/gateway';

@Module({
  imports: [
    McpGatewayModule.forRoot({
      name: 'my-gateway',
      version: '1.0.0',
      upstreams: [
        {
          name: 'weather',
          transport: {
            type: McpTransportType.STREAMABLE_HTTP,
            url: 'http://weather-service/mcp',
          },
        },
        {
          name: 'search',
          transport: {
            type: McpTransportType.STREAMABLE_HTTP,
            url: 'http://search-service/mcp',
          },
        },
      ],
    }),
  ],
})
export class AppModule {}

Tools from upstream servers are exposed with a prefix (weather_forecast, search_query). Downstream clients see one unified MCP server.

Features

• Automatic prefixing — tools, resources, and prompts are namespaced by upstream name
• Policy engine — allow/deny/require-approval rules per tool or upstream
• Response caching — TTL-based cache for tool results
• Request/response transforms — custom hooks to rewrite calls
• Health monitoring — periodic ping per upstream
• Task proxying — long-running tasks forwarded with upstream prefix
• Sampling & elicitation — forwarded transparently to the correct upstream

Documentation

Full documentation: github.com/btwld/nest-mcp/docs/gateway

License

BSD-3-Clause