Serve with Hono

npm install @modelcontextprotocol/server @modelcontextprotocol/hono hono

Mount the handler

createMcpHandler turns a server factory into a web-standard HTTP handler, and handler.fetch takes the Request a Hono route already holds as c.req.raw — no Node adapter. createMcpHonoApp is new Hono() with JSON body parsing and DNS rebinding protection already applied.

import { createMcpHonoApp } from '@modelcontextprotocol/hono';
import { createMcpHandler, McpServer } from '@modelcontextprotocol/server';
import type { Context } from 'hono';
import * as z from 'zod/v4';

const handler = createMcpHandler(() => {
    const server = new McpServer({ name: 'notes', version: '1.0.0' });
    server.registerTool('add-note', { description: 'Append a note', inputSchema: z.object({ text: z.string() }) }, async ({ text }) => ({
        content: [{ type: 'text', text: `Saved: ${text}` }]
    }));
    return server;
});

const app = createMcpHonoApp();
app.all('/mcp', (c: Context) => handler.fetch(c.req.raw, { parsedBody: c.get('parsedBody') }));

export default app;

app is an ordinary Hono app, and export default app is the { fetch } object Cloudflare Workers, Deno, and Bun serve directly; on Node, pass app to serve from @hono/node-server. The factory runs once per request, so a fresh McpServer serves every call: Serve over HTTP covers that model.

TIP

Keep the explicit c: Context annotation: on an inferred callback context c.get's key parameter narrows to never and c.get('parsedBody') does not compile.

Protect against DNS rebinding

A malicious page can DNS-rebind its own domain to 127.0.0.1 and reach a localhost server as if it were same-origin. createMcpHonoApp validates the Host and Origin headers against that: with the default 127.0.0.1 bind (and localhost / ::1), a request carrying a non-localhost value gets 403 before your handler runs.

Binding to all interfaces drops that default — name the hosts you serve instead.

const publicApp = createMcpHonoApp({ host: '0.0.0.0', allowedHosts: ['api.example.com'] });

allowedHosts and allowedOrigins take hostnames, port-agnostic. A request without an Origin header always passes, so MCP clients outside a browser are unaffected.

Forward auth and the parsed body

createMcpHonoApp parses JSON bodies into c.get('parsedBody') for you; keep passing it through. Auth travels the same way — handler.fetch's second argument is strictly pass-through, and handlers read it as ctx.http.authInfo.

publicApp.all('/mcp', async (c: Context) => {
    const authInfo = await verifyToken(c.req.raw);
    return handler.fetch(c.req.raw, { authInfo, parsedBody: c.get('parsedBody') });
});

verifyToken is your token verification. Authorization covers verifying bearer tokens and serving the OAuth metadata documents.

Run it and verify

Deploy the default export on any runtime that serves a { fetch } object — wrangler dev server.ts puts it on http://127.0.0.1:8787. POST a tools/list request to /mcp.

curl -s -X POST http://127.0.0.1:8787/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

The response is a single SSE message event carrying the tools/list result:

event: message
data: {"result":{"tools":[{"name":"add-note","description":"Append a note","inputSchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","properties":{"text":{"type":"string"}},"required":["text"]}}]},"jsonrpc":"2.0","id":1}

Recap

• One install line, one file: createMcpHonoApp() plus one app.all('/mcp', …) route over createMcpHandler(factory).fetch.
• Hono hands c.req.raw straight to handler.fetch — no Node adapter.
• A fresh server instance from your factory serves every request.
• The default 127.0.0.1 bind validates Host and Origin; pass allowedHosts when binding to 0.0.0.0.
• authInfo and parsedBody travel in handler.fetch's second argument; handlers read auth as ctx.http.authInfo.