typescript-sdk/packages/middleware/hono

@modelcontextprotocol/hono

Hono adapters for the MCP TypeScript server SDK.

This package is a thin Hono integration layer for @modelcontextprotocol/server.

It does not implement MCP itself. Instead, it helps you:

• create a Hono app with sensible defaults for MCP servers
• parse JSON request bodies and expose them as c.get('parsedBody') for Streamable HTTP transports
• add DNS rebinding protection via Host header validation (recommended for localhost servers)

Install

npm install @modelcontextprotocol/server @modelcontextprotocol/hono hono

Exports

• createMcpHonoApp(options?)
• hostHeaderValidation(allowedHostnames)
• localhostHostValidation()

Usage

Streamable HTTP endpoint (Hono)

import { McpServer, WebStandardStreamableHTTPServerTransport } from '@modelcontextprotocol/server';
import { createMcpHonoApp } from '@modelcontextprotocol/hono';

const server = new McpServer({ name: 'my-server', version: '1.0.0' });
const transport = new WebStandardStreamableHTTPServerTransport({ sessionIdGenerator: undefined });
await server.connect(transport);

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

Host header validation (DNS rebinding protection)

import { localhostHostValidation } from '@modelcontextprotocol/hono';

const app = createMcpHonoApp();
app.use('*', localhostHostValidation());