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

``bash
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)

`typescript
// 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:

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

For stdio-only clients, use mcp-remote:

`json
{
"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