/** * `createMcpHandler` with `responseMode: 'json'` — single JSON response * instead of an SSE stream. Useful for serverless deployments that can't * hold a stream open. Mid-call notifications are dropped (the handler logs a * warning at construction time). * * HTTP-only — `responseMode` shapes the HTTP response body; there is no stdio * equivalent and a stdio leg would not exercise the option. */ import { serve } from '@hono/node-server'; import { parseExampleArgs } from '@mcp-examples/shared'; import { createMcpHonoApp } from '@modelcontextprotocol/hono'; import { createMcpHandler, McpServer } from '@modelcontextprotocol/server'; import * as z from 'zod/v4'; function buildServer(): McpServer { const server = new McpServer({ name: 'json-response-example', version: '1.0.0' }); server.registerTool( 'greet', { description: 'A simple greeting tool', inputSchema: z.object({ name: z.string() }) }, async ({ name }) => ({ content: [{ type: 'text', text: `Hello, ${name}!` }] }) ); return server; } const { port } = parseExampleArgs(); // `responseMode: 'json'` is the point of this story — applies to the modern // (2026-07-28) per-request HTTP path. const handler = createMcpHandler(buildServer, { responseMode: 'json' }); // `createMcpHonoApp()` binds the endpoint behind localhost host/origin // validation by default, matching the framework factories' defaults. const app = createMcpHonoApp(); app.all('/mcp', c => handler.fetch(c.req.raw)); serve({ fetch: app.fetch, port, hostname: '127.0.0.1' }, () => { console.error(`[server] listening on http://127.0.0.1:${port}/mcp`); });