MCP's Biggest Rewrite Yet Ditches Sticky Sessions

The Model Context Protocol just dropped the release candidate for its 2026-07-28 spec, and it's the biggest revision since the protocol was born. The headline for anyone running MCP servers at scale: the core is now stateless. A remote server that used to need sticky sessions, a shared session store, and deep packet inspection at the gateway can now sit behind a plain round-robin load balancer, route on an Mcp-Method header, and let clients cache tools/list responses for as long as its ttlMs allows. In plain terms, MCP servers now scale like any other boring HTTP service.

There's more here than plumbing. The spec adds MCP Apps, which lets a server render actual UI instead of just returning text, and a Tasks extension for long-running work that doesn't fit inside a single request. Authorization gets pulled into line with real OAuth and OpenID Connect deployments, and for the first time there's a formal deprecation policy, the sign of a protocol that expects to be around for a decade rather than a season.

Why this matters: MCP won the connector war fast, but the early spec was built for a laptop talking to one server, not an enterprise fleet serving millions of agent calls. Stateless-by-default is the unlock that lets it graduate from demo glue to infrastructure. The final spec lands July 28. RC details at blog.modelcontextprotocol.io.