skillmcp

An MCP stdio server that makes skill packs callable by any agent — search them, fetch one, done. No copying folders into a prompt, no giant context dump.

Ships with 50 validated skills about running such a server: wiring clients, designing tools, invoking them cheaply, verifying the protocol, governing side effects and publishing packs.

skillmcp serve --packs-root /srv/packs     # JSON-RPC 2.0 over stdin/stdout
skillmcp tools                              # what this server advertises
skillmcp index --packs-root .               # packs and skills it can see
skillmcp call search_skills --args '{"query":"stdout purity"}'

Why a server instead of a directory

A skill directory only helps an agent that already knows the folder exists and can afford to read it. A server turns that directory into three calls:

So the agent searches with keywords, reads one procedure, and acts. Search covers slug, title, tags and the per-skill description, which is why a query like stdout purity finds exactly the right skill.

Related MCP server: skills.sh MCP Server

Protocol

Protocol revision pinned to 2025-03-26, newline-delimited JSON-RPC 2.0 over stdio. Implemented: initialize, notifications/initialized, ping, tools/list, tools/call. Everything else returns -32601.

$ printf '%s\n' \
  '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-03-26"}}' \
  '{"jsonrpc":"2.0","method":"notifications/initialized"}' \
  '{"jsonrpc":"2.0","id":2,"method":"tools/list"}' \
  '{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"search_skills","arguments":{"query":"stdout purity","limit":2}}}' \
  | skillmcp serve

{"id":1,"protocolVersion":"2025-03-26","capabilities":{"tools":{"listChanged":false}},"serverInfo":{"name":"skillmcp","version":"1.0.0"}}
{"id":2,"tools":["list_packs","search_skills","get_skill"]}
{"id":3,"matches":["stdout-purity-check"],"total":1}

Notifications never get a reply. Malformed lines get -32700 and the server keeps serving. stdout carries protocol messages only; diagnostics go to stderr, which the test suite asserts.

Client config

{
  "mcpServers": {
    "skills": {
      "command": "python",
      "args": ["-m", "skillmcp", "serve", "--packs-root", "/srv/packs"]
    }
  }
}

Point --packs-root at a directory of packs, or at a single pack. Anything with a pack.json is discovered, including packs built by the other repos in this series.

The 50 skills

skillmcp list --phase govern
skillmcp search stdout
skillmcp show protocol-conformance-test

Each skill renders deterministically from a Python corpus dict, carries a SHA-256 in pack.json, and is re-validated against six floors on every run.

Install

python -m venv .venv && . .venv/bin/activate     # Windows: .venv\Scripts\activate
pip install -e ".[dev]"
pytest -q
skillmcp serve --packs-root .

Python 3.10+. No runtime dependencies, and the server never opens a socket — stdio only.

Safety

The server is read-only: three tools, no writes, no network. It reads files under the packs root you give it and returns text. Credentials never belong in the client config; a server that needs one should read it from the environment, as secrets-via-environment describes.

MIT licensed.