Key Changes

This document lists changes made to the Model Context Protocol (MCP) specification since the previous revision, 2025-11-25.

Major changes

N/A

Minor changes

1. Add extensions field to ClientCapabilities and ServerCapabilities to support optional extensions beyond the core protocol.

Other schema changes

N/A

Governance and process updates

N/A

Process changes

1. Formalize PR-based SEP workflow with markdown files in seps/ directory, PR-derived numbering, sponsor responsibilities, and status management via PR labels (SEP-1850).

Full changelog

For a complete list of all changes that have been made since the last protocol revision, see GitHub.