MCP 2026 removes the session layer to make the protocol stateless

On 2026-07-28, a new version of the Model Context Protocol specification was published, removing the session layer entirely and making the protocol stateless. The article describes it as the biggest revision since the protocol launched in November 2024: the initialize handshake and the Mcp-Session-Id header are gone, and each request now carries its own protocol version and client capabilities. As a result, any server instance can answer any request, and an MCP server can scale like an ordinary web service behind round-robin load balancing. Mid-request callbacks are replaced by Multi Round-Trip Requests, MCP Apps and Tasks become official extensions, and OAuth iss validation becomes mandatory. Behavior for tools, resources, and prompts stays the same, and most tool code carries over unchanged.

On 2026-11-02, the Feedlio team published a piece on DEV Community about running MCP in production under the stateless 2026-07-28 specification. It notes that tools, resources, and prompts behave the same as before, so most tool code can be reused, and warns that the most common mistake is mirroring a REST API design by exposing one endpoint per tool and letting the model chain multiple calls, which is more error-prone and more token-hungry than designing aggregate tools like find_overdue_invoices. A follow-up DEV Community article on 2026-11-03, titled around MCP 2.0, walks through the same 2026-07-28 changes and focuses on migration steps. Coverage so far is limited to community write-ups and migration advice, and does not mention official migration guidance for the breaking change.