The Model Context Protocol uses string-based version identifiers following the format YYYY-MM-DD, to indicate the last date backwards incompatible changes were made.

Revisions

Revisions may be marked as:

  • Draft: in-progress specifications, not yet ready for consumption.
  • Current: the current protocol version, which is ready for use and may continue to receive backwards compatible changes.
  • Final: past, complete specifications that will not be changed.

The current protocol version is 2025-06-18.

Negotiation

Version negotiation happens during initialization. Clients and servers MAY support multiple protocol versions simultaneously, but they MUST agree on a single version to use for the session.

The protocol provides appropriate error handling if version negotiation fails, allowing clients to gracefully terminate connections when they cannot find a version compatible with the server.

Edit this page

Last updated 10 Aug 2025, 20:01 +0100 . history