mcp-handler

A Vercel adapter for the Model Context Protocol (MCP), enabling real-time communication between your applications and AI models. Supports Next.js and Nuxt.

Installation

npm install mcp-handler @modelcontextprotocol/sdk@1.25.2 zod@^3

Note: Versions of @modelcontextprotocol/sdk prior to 1.25.1 have a security vulnerability. Use version 1.25.2 or later.

Quick Start (Next.js)

// app/api/[transport]/route.ts
import { createMcpHandler } from "mcp-handler";
import { z } from "zod";

const handler = createMcpHandler(
  (server) => {
    server.registerTool(
      "roll_dice",
      {
        title: "Roll Dice",
        description: "Roll a dice with a specified number of sides.",
        inputSchema: {
          sides: z.number().int().min(2),
        },
      },
      async ({ sides }) => {
        const value = 1 + Math.floor(Math.random() * sides);
        return {
          content: [{ type: "text", text: `🎲 You rolled a ${value}!` }],
        };
      }
    );
  },
  {},
  {
    basePath: "/api", // must match where [transport] is located
    maxDuration: 60,
    verboseLogs: true,
  }
);

export { handler as GET, handler as POST };

Connecting Clients

If your client supports Streamable HTTP, connect directly:

{
  "remote-example": {
    "url": "http://localhost:3000/api/mcp"
  }
}

For stdio-only clients, use mcp-remote:

{
  "remote-example": {
    "command": "npx",
    "args": ["-y", "mcp-remote", "http://localhost:3000/api/mcp"]
  }
}

Documentation

• Client Integration - Claude Desktop, Cursor, Windsurf setup
• Authorization - OAuth and token verification
• Advanced Usage - Dynamic routing, Nuxt, configuration options

Features

• Framework Support: Next.js and Nuxt
• Multiple Transports: Streamable HTTP and Server-Sent Events (SSE)
• Redis Integration: Optional, for SSE transport resumability
• TypeScript Support: Full type definitions included

Requirements

• Next.js 13+ or Nuxt 3+
• Node.js 18+
• Redis (optional, for SSE)

License

Apache-2.0