If you build on the Model Context Protocol (MCP), the most useful news of the month is not a feature but a calendar. SEP-3398, a Specification Enhancement Proposal, sets two specification releases a year, in March and September. A maintainer recorded on 14 October 2026 that it "has been accepted", and it merged on 27 October. Adopt: pin to the current 2026-07-28 revision and put March 2027 in your calendar to review the next one.
What it changes
The proposal formalises a release process that the core maintainers put forward at MCPCon Europe. Releases come in March and September, with "overlapping eight-month cycles" and rotating release managers. It also covers a shared review queue for proposals, sponsorship of proposals by maintainers, voting by core maintainers, freeze dates and milestones for the software kits, and emergency approvals. A transition to March 2027 is proposed.