The MCP 2026-07-28 release candidate is not just a new SDK import path. It changes how hosts and servers agree on protocol version, state, discovery, server-to-client input, auth, and deprecated features.
Start With A Compatibility Lane
Keep production on the supported SDK line until the host and server both pass a compatibility check. Use a small non-production server to test v2 beta behavior, and list every host, server, transport, SDK, and auth path before changing defaults.
Prove The Protocol Era
Modern MCP requests carry protocol version, client identity, and capabilities in metadata, while servers advertise capabilities through discovery. Logs should make it obvious whether a request used the legacy or modern path.
- Can the host and server name the same protocol version?
- Can the gateway route without body inspection?
- Can traces show which era handled the request?
Replace Hidden Session State
The stateless core removes protocol-level sessions. Any workflow that needs continuity should use explicit handles such as task ids, browser ids, or workspace ids, with lifetime, ownership, revocation, and redaction rules.
Review Input Required As Approval
Server-to-client input now belongs in a request-scoped approval path. Treat delete, account, browser, credential, or production actions as explicit prompts with schemas, request state, retry behavior, and audit evidence.
Stop New Work On Deprecated Features
Roots, Sampling, and Logging still work during the deprecation window, but new product flows should not depend on them. Prefer explicit tool parameters, resource URIs, direct model-provider integration, stderr, and OpenTelemetry.
Promote Only With Proof
Before production rollout, capture a modern request, discovery output, a state-handle round trip, an input-required approval flow, issuer-aware auth behavior, and a trace that follows the host, SDK, MCP server, and downstream call.
Sources
- Model Context Protocol·Official doc·Core sourceMCP blog: 2026-07-28 specification release candidate
- Model Context Protocol·Official doc·Core sourceMCP draft specification changelog
- Model Context Protocol·Official doc·Supporting sourceMCP TypeScript SDK v2 beta documentation
- Model Context Protocol·Official doc·Supporting sourceSEP-2577: Deprecate Roots, Sampling, and Logging
