Skills Extension SEP — spec, URI scheme, and reference implementation

[olaservo]

Background

Successor to #43 (Draft MCP Skills Convention v0.1, now closed). The convention approach graduated to a formal Extensions Track SEP based on convergence across 4+ independent implementations of skill:// URIs.

See the closing comment on #43 for the full evolution from convention to SEP.

Active PRs

• Add draft SEP for Skills Extension #69 — Draft SEP for Skills Extension (spec document) — @pja-ant
• Update URI scheme proposal to decouple path from skill name #70 — URI scheme update (decoupling path from skill name) — @pja-ant
• Add TypeScript SDK and examples for the Skills Extension SEP #71 — Reference implementation with SDK, server, client, and sample skills — @olaservo

Scope

The SEP defines how skills are exposed over MCP using existing Resources primitives, covering:

1. Resource mapping — skill:// URI scheme with multi-segment paths, explicit SKILL.md in URIs
2. Discovery — skill://index.json well-known index resource, optional enumeration via templates
3. Reading — standard resources/read, relative path resolution
4. Security & trust — skills as untrusted model input, no implicit local execution
5. Implementation guidelines — host-level read_resource tool, SDK convenience wrappers
6. Extension declaration — io.modelcontextprotocol/skills in server capabilities

Content format is delegated entirely to the Agent Skills specification. Zero protocol changes required — existing clients see skills as ordinary resources.

Supersedes

• Draft MCP Skills Convention v0.1 #43 — Draft MCP Skills Convention v0.1 (closed)