skills-mcp

MCP server that exposes Claude Code style skills (SKILL.md folders) in any harness that supports MCP but not skills. Load the skill catalog, invoke a skill by id, and read its files, all through four small tools.

What it does

• load-skills must be called once at the start of a session. It returns the catalog of every registered skill (name, description, model-invokable flag, when_to_use) and the exact rules for invoking them.

• skill loads one skill's full instructions by id. Skills marked disable_model_invocation: true require user_approved: true, the MCP analogue of user-only invocation.

• list-skill-files lists the files a skill directory ships.

• read-skill-file reads one file inside a skill directory (references/, scripts/, templates/), rejecting paths that escape the skill root.

The server parses SKILL.md exactly as Claude Code does: YAML frontmatter between --- markers, with the full community field set passing through untouched (name, description, when_to_use, version, license, author, allowed_tools, argument_hint, arguments, disable_model_invocation, user_invocable, model, effort, context, agent, shell, paths, compatibility, metadata).

Only the four tools are registered, so the model sees a small, stable tool surface. The catalog loads skill frontmatter at session start; skill bodies load on demand when a skill is invoked.

Related MCP server: Skill-to-MCP

Build

npm install
npm run build

dist/index.cjs is a single self-contained CommonJS bundle (esbuild), startable with node dist/index.cjs or directly via its shebang. It has no runtime dependencies, so the file alone is the whole server. Pass it to any MCP-capable harness.

Run

The server reads skills from a directory resolved in this order:

1. --skills <dir> argument

2. SKILLS_MCP_DIR environment variable

3. <cwd>/skills

node dist/index.cjs --skills /central/path/to/skills

Claude Desktop example:

{
  "mcpServers": {
    "skills": {
      "command": "node",
      "args": ["/home/you/skills-mcp/dist/index.cjs", "--skills", "/central/path/to/skills"]
    }
  }
}

Skills directory layout

Any of:

• ~/.claude/skills/<skill-name>/SKILL.md (personal)

• <project>/.claude/skills/<skill-name>/SKILL.md (shared)

• any folder you point --skills at, as long as each skill lives in its own subdirectory with a SKILL.md entry file.

A skill without a SKILL.md falls back to the first *.md in its directory.

Invoking skills

MCP has no user/model sender distinction, so disable_model_invocation maps to a gate on the skill tool: a matching skill returns an error unless the model passes user_approved: true. That flag must come from an explicit user request, per the instructions returned by load-skills.

Development

• npm run typecheck (tsc --noEmit)

• npm run build (esbuild -> dist/index.cjs)

• npm test (test/client.mjs, an end-to-end stdio session against the built bundle)

Releases

.github/workflows/release.yml builds on a v* tag push, runs typecheck, build, and test, then packages dist/index.cjs as skills-mcp-<tag>.cjs plus a .cjs.gz and SHA256SUMS.txt, and attaches them to a release.

Push a tag to release:

git tag v1.0.0 && git push origin v1.0.0

It can also run manually (Actions -> release -> Run workflow), optionally passing a tag name; otherwise it derives one from package.json and creates the release at the current commit.

Tag pushes skip packaging and release steps when nothing meaningful changed since the previous release. GitHub ignores paths filters for tag pushes, so this is a diff inside the job against the prior tag. Meaningful paths: src/, skills/, package.json, package-lock.json, tsconfig.json, and the workflow itself. Manual runs always release.

Source lives in src/:

• src/mcp/protocol.ts minimal spec-correct MCP stdio server (JSON-RPC framing, initialize, ping, tools/list, tools/call)

• src/skills/frontmatter.ts SKILL.md frontmatter + body splitting, YAML via the yaml package

• src/skills/registry.ts directory discovery with mtime-based cache

• src/skills/types.ts Skill/SkillMeta model

• src/tools/index.ts the four tool definitions and handlers

• src/index.ts entry point and skills-dir resolution