Latest MCP spec now supported in mcp-handler
By Steven Van ·
mcp-handler 2.0 needs Node.js 20 and zod4, drops the old SSE transport, and runs both MCP protocols without Redis.
Vercel's mcp-handler library has reached version 2.0, adding support for the 2026-07-28 Model Context Protocol specification and the MCP TypeScript SDK v2. Built to make it easier to run MCP servers on frameworks like Next.js, Nuxt and Svelte, the handler now serves the new stateless protocol natively, including per-request metadata and server/discover, while keeping a stateless compatibility layer for clients still on 2025-era Streamable HTTP. Neither path needs Redis or session storage, and existing Streamable HTTP clients can keep connecting to the same /mcp endpoint as servers move to the new protocol.
The update also carries breaking changes for anyone upgrading:
- Version 2 requires Node.js 20 or later and zod4, and replaces @modelcontextprotocol/sdk with @modelcontextprotocol/server.
- Tool, prompt and resource definitions now use the SDK v2 registration APIs and Standard Schema inputs, such as registerTool with z.object(...).
- The deprecated HTTP+SSE transport has been removed: requests to /sse and /message now return 410 Gone. Projects still depending on it should stay on mcp-handler 1.x while migrating to Streamable HTTP.
