Skillguard MCP server

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SkillGuard

Install • Try it now • Features • MCP server • How it compares • FAQ

Scans third-party AI agent-skill files (SKILL.md manifests, hooks, and bundled scripts) for known attack patterns before they run, and is the only scanner in its category you can also call as an MCP tool from inside another agent.

Install

# npm -- JavaScript/TypeScript CLI + library
npm install --save-dev skillguard-cli

# PyPI -- Python CLI + library, a genuine port, not a wrapper around the Node binary
pip install skillguard-cli

Neither install fetches anything at scan time: all ten rule packs and the pattern-matching engine ship inside the npm tarball and the Python wheel alike.

Try it now

npx skillguard-cli scan ./examples/known-bad-skill

This runs against a fixture bundled with the repo, safe, non-functional, and deliberately pattern-matchable, and returns 11 real findings with file:line citations in about 0.15 seconds.

[!NOTE]

Every scan prints Loading SkillGuard rule packs... to stderr first. That's expected startup output, not a hang.

Compare it against a clean fixture:

npx skillguard-cli scan ./examples/clean-skill

which returns zero findings and exit code 0.

Why this exists

Third-party agent skills run with real tool, file, and network permissions the moment they're installed, and almost nothing checks them first. Snyk's ToxicSkills study scanned 3,984 publicly listed skills in February 2026 and found security flaws in 36% of them, including 76 skills carrying confirmed malicious payloads: credential theft, reverse shells, data exfiltration. Most marketplaces and agent frameworks have no scan step between "someone published a skill" and "a user's agent runs it." SkillGuard is that step: a CLI, a library, an MCP server, and a GitHub Action, all reading the same ten bundled rule packs.

Features

Shortened. The full README is on GitHub.