skill-guard

Pre-install security check for Agent Skills.
Scan a SKILL.md package before your agent loads it. Offline, deterministic, no code execution.

Part of aisona-lab trust tooling (prompt-guard, OrcaI, lazycoder).
Beta · LIMITATIONS · CHANGELOG

Who this is for

Not a runtime firewall. Not an MCP auditor. Static pre-install only.

Try it in 30 seconds

# install CLI (package name on PyPI ≠ CLI name)
uv tool install aisona-skill-guard
# if PyPI is empty yet:
# uv tool install "git+https://github.com/aisona-lab/skill-guard@v0.2.2"

git clone --depth 1 https://github.com/aisona-lab/skill-guard.git /tmp/skill-guard
cd /tmp/skill-guard

skill-guard scan dataset/fixtures/benign/tdd-checklist
# → ALLOW  exit 0

skill-guard scan dataset/fixtures/malicious/curl-pipe-shell
# → BLOCK  exit 2  (SG003: curl | bash)

skill-guard scan dataset/ood/safe/vercel/deploy-to-vercel
# → WARN   (SG006: npm install -g in a fenced install step)

What it looks like

Malicious fixture (curl … | bash):

skill-guard  verdict=BLOCK  exit=2
[CRITICAL] SG003  Pipe remote content into a shell
  evidence: curl | … | bash

Real public skill (Vercel deploy — legitimate but global install):

skill-guard  verdict=WARN  exit=1
[MEDIUM] SG006  Global package install from skill
  at: SKILL.md:141
  evidence: npm install -g

Clean skill (ponytail / in-repo benign):

skill-guard  verdict=ALLOW  exit=0
No findings.

Live results on real corpora (v0.2.2)

Policy: --fail-on block (WARN does not fail CI by default).

Reproduce gates:

uv run python eval/run_eval.py --suite all --check
uv run pytest -q

Rules (why they matter)

Examples and nuance: docs/RULES.md.

Install & CI

pip install aisona-skill-guard   # CLI: skill-guard
# package name on PyPI is aisona-skill-guard (skill-guard is unrelated)

- uses: aisona-lab/skill-guard@v0.2.2
  with:
    path: ./skills/my-skill
    fail-on: block

# .skill-guard.yml
pack: default   # or strict
suppress: [SG008]

Status & maintenance

Issues and security notes: GitHub · LIMITATIONS · BENCHMARKS

License

MIT © aisona-lab