AWS AgentCore Gateway adds support for MCP's largest protocol revision, making it stateless over plain HTTP

AWS announced on July 28, 2026 that AgentCore Gateway now supports the 2026-07-28 revision of the Model Context Protocol (MCP), which the post describes as the protocol's biggest change since it launched — converting MCP from a stateful, session-based protocol into one that runs on ordinary HTTP infrastructure.

What's new

AWS's blog post is direct about the scope of the change: "With this release MCP becomes a stateless protocol that scales on ordinary HTTP infrastructure." Previously, MCP servers needed to maintain protocol sessions and, in many deployments, sticky sessions or a shared session store to keep a client pinned to the right backend instance. The 2026-07-28 spec removes that requirement entirely.

Key changes AWS highlights:

• Removal of protocol sessions — no more server-side session state that has to be tracked or replicated.
• Standardized HTTP headers for routing — requests can be routed using ordinary HTTP infrastructure (load balancers, gateways) instead of protocol-aware session affinity.
• Explicit freshness metadata — responses now carry caching information, so intermediaries can cache safely.
• A governed extensions system — a structured way for the spec to grow without breaking existing clients.

AgentCore Gateway customers can opt in by calling UpdateGateway with the new protocol version listed in supportedVersions. Existing clients are unaffected: version selection happens per-request via the MCP-Protocol-Version header, so a gateway can serve both the old and new spec simultaneously during migration.

Context

MCP has become the default protocol for connecting AI agents to external tools and data sources since Anthropic introduced it, with adoption from most major labs and cloud providers building agent infrastructure. But the original stateful design was a known pain point for anyone trying to run MCP servers behind standard cloud load-balancing infrastructure — sticky sessions and shared session stores add operational complexity that ordinary REST APIs don't need.

AWS's AgentCore Gateway is the managed service AWS offers for exposing tools to agents via MCP, so this is AWS moving quickly to support the updated spec on its own managed infrastructure rather than waiting for third-party servers to catch up.

Why it matters

For teams building or operating MCP servers at scale, statelessness is an operational simplification, not just a spec detail: it means MCP servers can be deployed and scaled the same way as any other HTTP API, using existing load balancers, autoscaling groups, and caching layers, instead of needing purpose-built session-affinity infrastructure. That lowers the bar for running MCP in production at meaningful scale.

AWS shipping support for this within a day of the spec revision is also a signal about how central MCP has become to cloud providers' agent strategy — infrastructure vendors are now tracking and implementing protocol changes on a near-immediate cadence, treating MCP compatibility as table stakes for agent tooling rather than an optional integration.