MCP goes stateless: the 2026-07-28 spec ships with Tier 1 SDKs live

The Model Context Protocol's fifth revision replaces the stateful session model with a stateless request/response core, graduates Tasks and MCP Apps as official extensions, and lands across all four Tier 1 SDKs on day one.

The Model Context Protocol maintainers published the 2026-07-28 specification today, tearing out the bidirectional stateful session model that defined MCP’s first year and replacing it with a stateless request/response core that carries routing information in HTTP headers. It’s the fifth revision of the protocol and, by the maintainers’ own reckoning, the largest since authorization was added.

Lead maintainer David Soria Parra didn’t soften the framing. “A lot of things that made MCP are gone,” he said on a livestream the week before release, describing the underlying data-transfer mechanism as “totally been rebuilt.” That’s not a patch note. That’s an admission that the shape of the protocol has changed.

Two extensions graduate alongside the core. Tasks, contributed by AWS, becomes an official extension under the identifier io.modelcontextprotocol/tasks, with SEP-2663 defining a poll-based tasks/get and a new tasks/update. MCP Apps ships in parallel under the versioned extensions framework, letting servers render interactive UI inline in conversations. Change notifications consolidate to subscriptions/listen.

SEP-2577 formally deprecates Roots, Sampling, and Logging, along with Dynamic Client Registration and the legacy HTTP+SSE transport. The maintainers guarantee deprecated features will keep working for at least twelve months. Stacklok’s enterprise readiness guide flags the obvious caveat: that window isn’t a blanket interoperability promise, and 2026-07-28 servers may not talk to older clients without deliberate fallback logic.

The scale numbers explain why the maintainers can afford to break things. All four Tier 1 SDKs support the new spec at launch, with the Rust SDK in beta. TypeScript and Python have each crossed one billion cumulative downloads. Maintainers report close to half a billion monthly SDK downloads across Tier 1; Anthropic puts the figure at 400 million monthly, a 4x increase this year, with over 950 servers in Claude’s connectors directory.

Day-zero support comes from Amazon Bedrock AgentCore, Cloudflare Agents SDK, and the Figma MCP server. Google Cloud and Anthropic are framing the release as the foundation for enterprise-scale agent deployment, which is the tell: MCP is being rewritten not for the hobbyist server authors who built its early lore, but for the platform teams who are about to run it in production.

MCP goes stateless: the 2026-07-28 spec ships with Tier 1 SDKs live

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