AWS announced support for the Model Context Protocol (MCP) 2026-07-28 specification, which marks the largest and most significant revision of the protocol since its launch. The update makes MCP stateless, allowing it to scale on standard HTTP infrastructure. This change enables enterprises to manage large-scale deployments more efficiently by eliminating the need for sticky sessions or shared session stores. Users can now update their AgentCore Gateway to support the new version without disrupting existing clients.
The new MCP version includes a governed extensions system, stronger authorization through OAuth 2.0 and OpenID Connect alignment, and lifecycle guarantees to prevent future breakage. These changes aim to support protocol evolution without compromising core capabilities. Upgrading is optional, and nothing changes until both the gateway and clients adopt the new version. AgentCore Gateway advertises supported protocol versions through a single configuration field, allowing clients to select a version on each request.
The specification transition to statelessness removes the need for an initialization handshake and session-based routing. Instead, every request now includes protocol version, client info, and capabilities within the _meta parameter. This makes each tool call self-contained and allows it to be routed to any server instance. The update also introduces new headers for routing, caching, and tracing without parsing the JSON-RPC body, improving compatibility with standard HTTP infrastructure.
Source: awsml
