Model Context Protocol: 2026-07-28 specification revision released as stable

The 2026-07-28 revision of the Model Context Protocol specification was published as a stable release on 2026-07-28, following a release candidate on 2026-05-29. The release note points to the specification at modelcontextprotocol.io and to the revision's changelog for the list of changes. Sources: 2026-07-28 release, changelog.

Relation to the directory: this is the latest tagged release of the spec repository as of 2026-09-30. SDK and framework support for a given revision varies; each tool page's MCP cell links to that tool's own evidence. See MCP, A2A vs MCP and the protocol matrix.