MCP Skills Extension (SEP-2640)

What it does

• Stable specification at specification/stable/skills.mdx — written against base protocol revision 2026-07-28, released as snapshots rather than edited in place
• Changes flow through an ADR-lite decision log: dated proposals, and accepted entries land in a draft revision that ships as the next release
• The docs folder carries the decision log, the design rationale for the Resources-based approach, and an implementations list of servers, SDKs and hosts serving or consuming skills over MCP
• Working-group machinery in the open: charter, project board, meeting notes and a Discord channel, with pull requests and issues welcoming in-flight contributions

When to use it

Server authors deciding whether to expose skills as MCP Resources; SDK maintainers tracking what to implement next; client authors checking the client matrix before claiming support. Also the reference for how an MCP extension actually gets made, end to end.

Getting started

No install — a specification repo. Read the stable spec for normative text, the overview docs on modelcontextprotocol.io for condensed message flow and examples, and the client matrix to see who implements it today.

Things to know

It's an extension, not core protocol: clients implement it optionally, and the client matrix exists precisely because support is not universal. The stable snapshot is never edited in place, so decisions accepted after its release live only in draft revisions until the next drop.