The Model Context Protocol is about to change in a fundamental way. The MCP 2026-07-28 specification release candidate — announced May 21, 2026 by lead maintainers David Soria Parra and Den Delimarsky — is the largest revision to the protocol since its launch. At the center of it is a single architectural decision that will ripple through every MCP server and client implementation in existence: MCP is going stateless.
The formal specification ships July 28, 2026. Until then, this is a look at what’s coming and why it matters.
The Core Change: Sessions Are Gone
Today’s MCP requires an initialization handshake at the start of every connection. Clients and servers exchange capability declarations, negotiate protocol versions, and establish a session context. That session context is then maintained for the lifetime of the connection — which means MCP servers need to track session state, and the infrastructure hosting those servers needs to ensure that requests from a given client land on the same server instance.
The release candidate eliminates all of that. Every MCP request becomes self-contained. No initialization handshake. No session IDs. No mandatory session state.
The practical infrastructure effect, straight from the announcement: 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. Requests can be routed on an Mcp-Method header. Clients can cache tools/list responses for as long as the server’s ttlMs permits.
For teams running MCP servers at scale, this is transformative. Stateful session management is expensive, fragile, and a significant operational burden. The stateless design removes that burden entirely.
The Full Feature Set
The stateless core is the headline, but the RC includes a substantial set of additional changes:
Extensions framework and MCP Apps — Extensions become first-class citizens in the protocol. MCP Apps introduces server-rendered user interfaces, allowing MCP servers to deliver interactive UI components. This is a major addition that moves MCP from a pure tool/data protocol toward a richer application-layer protocol.
Tasks graduates to an extension — The Tasks capability, which enables long-running work tracking, moves from an experimental feature to a formal Extension with a stable API surface.
Authorization hardening — The authorization model is being aligned more closely with OAuth 2.0 and OpenID Connect deployments. This addresses a real pain point: MCP’s current auth model has been inconsistently implemented across clients and servers. A spec-level alignment with established standards should significantly improve interoperability.
Deprecations: Roots, Sampling, and Logging — Three current protocol features — Roots, Sampling, and Logging — are formally deprecated in this RC. Teams relying on these will need to migrate; the announcement includes a formal deprecation policy going forward.
Full JSON Schema 2020-12 for Tools — Tool schemas are upgraded to full JSON Schema 2020-12 support. This enables more expressive and precise tool definitions, which matters for agentic systems that need to reliably parse and validate tool interfaces.
What “Breaking Changes” Means in Practice
The announcement is explicit: this release contains breaking changes. Here’s what to expect:
- Existing session-based MCP servers will need to be rewritten. The initialization handshake and session management logic don’t have an equivalent in the stateless design. This isn’t a backward-compatible change.
- The Tasks API changes. If you’re using Tasks in its current form, the Extension version has a different API surface.
- Deprecated features will eventually be removed. The formal deprecation policy means Roots, Sampling, and Logging have a finite lifespan in the spec.
The silver lining: the stateless design is actually simpler to implement than the session-based model. Rewriting an existing MCP server to be stateless should be significantly less code than the original implementation.
Timeline and Framing
Important framing note from the Analyst’s handoff: The formal RC is not yet final — it targets July 28, 2026. Current references are to in-progress spec work. The announcement published May 21 describes what’s coming, not what’s already shipping. Frame your planning accordingly: prepare for these changes, but don’t treat the RC as final until July 28.
A migration guide for the stateless redesign (“Migrating Your MCP Server to the Stateless Core”) will be worth commissioning once the RC is formally published. Watch this site in July for that coverage.
Why This Matters for Agentic AI
MCP has emerged as a critical piece of infrastructure for agentic systems. If you’re building agents that use tools — and almost all serious agentic systems do — you’re either using MCP or you’re building something that converges toward MCP’s design decisions.
The stateless redesign removes one of the biggest operational barriers to running MCP at scale. Horizontal scaling, load balancing, and cache-able tool discovery are standard infrastructure primitives. MCP servers that support these patterns are dramatically easier to operate than session-stateful alternatives.
This spec revision is the kind of foundational work that doesn’t ship until the ecosystem has enough production experience to know what’s actually painful. The fact that it’s happening now suggests the MCP ecosystem has grown to a scale where these operational concerns are real.
The July 28 final spec date is worth adding to your calendar.
Sources
- MCP Blog: The 2026-07-28 Specification Release Candidate — official announcement by MCP lead maintainers
- Model Context Protocol Documentation — protocol reference and current spec
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