The Model Context Protocol has published its 2026-07-28 Release Candidate — and if you’re building MCP servers, clients, or skills, you need to understand what’s changing. The lead maintainers, David Soria Parra and Den Delimarsky, describe it as “the largest revision of the protocol since launch.” That’s not marketing language. This RC contains breaking changes and restructures the protocol’s core architecture.

The final spec ships July 28. SDK maintainers and skill authors have until then to validate their implementations. With the MCP Dev Summit arriving in Mumbai on June 14-15 (co-hosted by the Linux Foundation’s Agentic AI Foundation), this RC is the live topic of conversation for the MCP ecosystem right now.

Here’s what’s actually changing.

A Stateless Protocol Core — The Headline Change

The biggest architectural shift in this RC is the removal of mandatory session handshakes from the protocol core.

In the previous MCP design, servers needed to maintain session state — tracking which client was which, preserving context across a connection, managing session lifecycle. In practice, this meant you needed sticky sessions at your load balancer, a shared session store, and careful gateway configuration if you wanted to run anything at scale.

The new stateless core removes all of that as a protocol requirement. Per the official MCP blog post: “A remote MCP server that previously needed sticky sessions, a shared session store, and deep packet inspection at the gateway can now run behind a plain round-robin load balancer, route traffic on an Mcp-Method header, and let clients cache tools/list responses for as long as the server’s ttlMs permits.”

This is a significant infrastructure simplification for anyone running MCP servers in production. The catch: it’s a breaking change for existing implementations that rely on session state.

Stateless protocol, stateful applications: Critically, this doesn’t mean your applications must be stateless. The protocol layer is stateless; the application layer can still maintain whatever state it needs. The distinction matters: MCP isn’t forcing you to redesign your application, it’s just cleaning up the protocol surface.

Extensions Become First-Class

The RC formalizes an Extensions framework that brings two significant new capabilities:

Tasks

Long-running work gets a first-class mechanism. The Tasks extension allows MCP servers to represent work that takes time — background jobs, multi-step processes, async operations — without requiring the client to maintain an open connection for the duration. This is something that came up repeatedly in real-world deployments where agentic tasks might run for minutes or hours.

MCP Apps

MCP Apps adds support for server-rendered user interfaces. An MCP server can now serve a lightweight UI that clients can display. This opens up a category of interactive, server-driven experiences within the MCP model that wasn’t previously possible — think rich result displays, configuration UIs, or approval workflows embedded directly in the MCP interaction.

Authorization Hardening — OAuth 2.1 and OpenID Connect

The authorization model gets a meaningful upgrade in this RC, aligning more closely with OAuth 2.1 and OpenID Connect deployments. The previous auth story was underspecified in ways that led to inconsistent implementations. This RC tightens the spec to reflect how real-world OAuth/OIDC systems actually work.

If you’ve built custom auth on top of MCP, this is another area to review carefully before July 28.

What’s Being Deprecated

Three components are formally deprecated in this RC:

  • Roots
  • Sampling
  • Logging

The deprecation of Sampling is likely to be the most impactful for current implementations. This is an area where many skill/plugin authors have built functionality. The formal deprecation policy (new in this RC) means these won’t disappear immediately, but the clock is ticking.

Full JSON Schema 2020-12 for Tools

Tool definitions now support full JSON Schema 2020-12. This is a capability upgrade for anyone building tools with complex input shapes — you can now express more precise constraints, use newer schema features, and get better validation behavior.

What This Means for OpenClaw Users

For OpenClaw users specifically: the stateless core changes affect how MCP servers are deployed and integrated. The Skills system in OpenClaw uses MCP concepts extensively, and the RC’s breaking changes to session handling, deprecations, and auth may require updates to skills that talk to external MCP servers.

The good news: the MCP team has committed to a formal deprecation policy going forward, meaning future breaking changes will come with advance notice and migration windows. The July 28 deadline is the right time to review your MCP integrations.

Key Dates

  • RC available: May 21, 2026
  • Final spec: July 28, 2026
  • MCP Dev Summit Mumbai: June 14-15, 2026 (Linux Foundation / AAIF)

Sources

  1. Official MCP Blog — 2026-07-28 Release Candidate
  2. AAIF.io analysis of MCP RC
  3. MCP Dev Summit Mumbai — Linux Foundation

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