MCP Specification Release Candidate for 2026-07-28 Published

The MCP 2026-07-28 release candidate is the largest specification revision since launch, reflecting the core initiatives of the 2026 roadmap. This release includes Breaking Changes, so caution is required.

The main updates are as follows:

• Stateless core: a structure that scales easily across common HTTP infrastructure
• Extensions: server-rendered UI via MCP Apps and support for long-running operations via the Tasks extension
• Authorization: authorization aligned with OAuth and OpenID Connect
• Official deprecation policy: a framework for the protocol's continued evolution

The most central change is that the protocol layer has shifted to being stateless. Previously, calling a tool required going through an initialize handshake to obtain and maintain an Mcp-Session-Id, but now every request is handled as a single, independent request containing all necessary information.

As a result, session management is no longer needed at the protocol layer. This means MCP servers can be scaled horizontally through a standard round-robin load balancer, without sticky sessions or a shared session store. Clients pass the protocol version and client information via the _meta field, and query server capabilities using the server/discover method.

Even though the protocol has become stateless, if application state still needs to be maintained, this can be implemented—similar to an HTTP API approach—by having a tool generate an explicit handle (e.g., basket_id) that the model then passes back.