# Building efficient MCP servers By Steven Van · 2025-06-12 The MCP adapter now supports Streamable HTTP alongside SSE, with an option to turn SSE off for MCP servers built on Next.js, Nuxt, or SvelteKit. The MCP adapter that lets developers build [Vercel]() MCP servers with frameworks like Next.js, Nuxt, and SvelteKit now supports Streamable HTTP, the transport the Model Context Protocol specification adopted in March 2025 to replace Server-Sent Events (SSE). The original MCP spec, published in November 2024, supported only stdio and SSE. SSE keeps a persistent connection open between client and server even when idle, which Vercel says remains an inefficient choice for MCP servers at scale even with Fluid compute reusing allocated servers. Streamable HTTP removes the need for that persistent connection. Because adoption of the newer transport has been slow, many MCP clients still support only stdio and SSE, so the adapter now offers built-in support for both Streamable HTTP and SSE, with the option to disable SSE for servers that want to align fully with the newer spec. Vercel says production apps including Zapier, Composio, Vapi, and Solana use the adapter to deploy their own MCP servers, and that clients like Cursor, Claude, and Windsurf now support connecting to MCP servers and calling their tools. Read the [full announcement](). [![]()]() ![Vercel]() Vercel The platform for frontend developers — deploy, preview, and scale web apps and AI agents with zero config. [View Vercel →]() [Original source]() [Read Building efficient MCP servers on Creators Toolbox]() --- Canonical source: https://creatorstoolbox.com/blog/vercel-building-efficient-mcp-servers