MCP Server transport for Hono applications

用于 Hono 应用的 MCP 服务传输层

概述

本项目为需要连接 MCP 服务的 Hono 应用提供了一种传输层。官方 TypeScript SDK 是为与 express 配合使用而设计的。 如果你尝试按照他们的说明操作，只是把 express 换成 hono，你会发现它无法工作。即使你将 HttpBinding 设置为环境变量（参见 @hono/node-server 的示例）， 它仍然无法工作，因为某些响应头会在响应发送之后才被添加到响应中。

本实现受到了以下 pull request 的启发。

在官方 SDK 正式支持 Hono 之前，你可以使用这个传输层。

快速开始

安装

pnpm add -D hono-mcp-server-sse-transport

用法

import { Hono } from 'hono';
import { serve } from '@hono/node-server';
import { streamSSE } from 'hono/streaming';
import { SSETransport } from 'hono-mcp-server-sse-transport';
import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';

const mcpServer = new McpServer(
  {
    name: 'your-mcp-server-name',
    version: '1.0.0',
  },
  {
    capabilities: {
      tools: {},
    },
  },
);

// here you add your tools
// ...

const app = new Hono();

// to support multiple simultaneous connections we have a lookup object from
// sessionId to transport
const transports: { [sessionId: string]: SSETransport } = {};

app.get('/sse', (c) => {
  return streamSSE(c, async (stream) => {
    const transport = new SSETransport('/messages', stream);

    transports[transport.sessionId] = transport;

    stream.onAbort(() => {
      delete transports[transport.sessionId];
    });

    await mcpServer.connect(transport);

    while (true) {
      // This will keep the connection alive
      // You can also await for a promise that never resolves
      await stream.sleep(60_000);
    }
  });
});

app.post('/messages', async (c) => {
  const sessionId = c.req.query('sessionId');
  const transport = transports[sessionId];

  if (transport == null) {
    return c.text('No transport found for sessionId', 400);
  }

  return await transport.handlePostMessage(c);
});

serve(
  {
    fetch: app.fetch,
    port: 3000,
  },
);