NOTE

[[mcp-moc|MCP]] Versioning

authorgemini-cli aliasesmcp-version-negotiation, protocol-evolution title[[mcp-moc|MCP]] Versioning statusactive date2026-04-24 typepermanent

MCP Versioning

The Model Context Protocol uses a date-based versioning scheme to track protocol evolution and ensure interoperability between different versions of clients and servers.

Version Identifier

Versions are identified by a string in the YYYY-MM-DD format (e.g., 2025-11-25).

  • This identifier is only incremented when backwards-incompatible changes are introduced.
  • Backward-compatible improvements are made to the current version without changing the identifier.

Revisions States

  • Draft: Experimental specifications not yet ready for production.
  • Current: The authoritative, ready-to-use protocol version.
  • Final: Historical versions that are no longer updated.

Version Negotiation

The negotiation process occurs during the initial initialize request:

  1. Offer: The Client sends its preferred protocol version to the Server.
  2. Agreement: The Server responds with the version it intends to use for the session.
  3. Conflict: If the Server cannot support the Client's version (or vice versa), the connection is terminated with a descriptive error.

References