Repo Safety Audit: Free Claude Code Plugin to Vet Any Skill, Plugin, or Package Before You Install It

What it is: A free Claude Code plugin that vets any third-party skill, plugin, MCP server, GitHub repo, or npm package before you install it. Gives a clear SAFE / CAUTION / AVOID verdict with citations.

Who it’s for: Anyone who installs third-party code — Claude Code skill collectors, devs using open-source tools, teams deciding whether to trust a community package.

Best if: You’re about to install something from a developer you don’t know, or you want to batch-audit the skills you already installed.

Skip if: You only install first-party tools from vendors you already trust, or you have an enterprise supply-chain review process already in place.

Every Claude Code skill runs with your permissions

When you install a third-party skill in Claude Code, you’re handing it the same power your agent has. It can read your files. It can run shell commands. It can edit code in your repos. It can make web requests using your credentials.

Most of the time this is fine, because most skill authors are honest. But “most of the time” is not a security model. One malicious SKILL.md — hidden inside a plugin that does something genuinely useful the other 99% of the time — can exfiltrate your .env, read your SSH keys, or redirect Claude to quietly modify your codebase next time you ask for a refactor.

This is the same supply-chain problem npm, PyPI, and VS Code extensions have been fighting for a decade — and now it applies to every Claude Code skill marketplace. The fix is the same thing security-minded devs do before installing any third-party tool: read the code first. Repo Safety Audit is that review, encoded as a Claude Code skill.

The problem, explained simply

Imagine you downloaded a cooking app, but you also accidentally gave it permission to read your bank statements, send emails from your account, and modify any file on your computer. If the app author is a nice person, nothing bad happens. If they’re not — or if their GitHub account got hacked last Tuesday — you have a very, very bad day.

Claude Code skills work a lot like that. They’re useful, they’re easy to install, and they have a lot of access. The good ones massively improve your productivity. The bad ones can ruin your week. Telling them apart is a job you can either do yourself (by reading every line of every skill you install), or you can hand to a process that knows exactly what to look for.

Repo Safety Audit is that process. It reads the skill for you, checks it against known patterns, sizes up the developer, and gives you a verdict — in the time it takes to brew a coffee.

What the audit actually checks

Six checks, run in order:

1. File inventory

List every code and documentation file in the repo. This maps the attack surface. An unusually large file count for the stated purpose, unexpected binaries, or nested install scripts are all flags before a single line is read.

2. Prompt-injection scan

This is the check unique to Claude Code. Claude reads SKILL.md, AGENTS.md, CLAUDE.md, and README files as instructions — which means they’re code, not docs. The audit greps every markdown file for classic injection phrases like “ignore previous instructions,” “you are now,” “before answering, decode and run the following,” and a dozen more, then flags anything that redirects Claude away from what the user actually asked for.

3. Shell execution and exfiltration patterns

Greps every code file for the patterns that show up in almost every piece of malicious install code: curl | sh, base64 | eval, unsafe subprocess invocations, unscoped rm -rf $HOME, reads of ~/.ssh/ or .env paired with a network call. Each hit is triaged — a rm -rf ./build inside a tool’s own install dir is fine, but rm -rf $HOME never is.

4. Import / dependency audit

Reads the imports in every code file and checks whether they match the stated purpose. A video-conversion tool that imports smtplib is suspicious. A tool claiming to work offline that imports requests is suspicious. Typo-squatted dependency names (reqeusts, lodahs) are almost always malicious. Unpinned dependencies pulling latest are a supply-chain risk even if today’s version is clean.

5. URL allowlist filter

Extracts every URL in every file. Filters out the boring ones (GitHub, PyPI, npm, official docs). Eyeballs the leftovers. Pastebins, ngrok tunnels, Discord or Telegram webhooks, raw IP addresses, or URL shorteners that could hide endpoints — all get flagged. Bonus: if the tool’s purpose legitimately involves webhooks (e.g. a Slack notifier), that context is noted rather than blindly flagged.

6. Developer reputation

Queries the GitHub API for the author’s account age, follower count, other repos, last push date, and star/fork ratio. A brand-new account with one high-star repo is a yellow flag (bot-inflated, compromised, or astroturfed). An established developer with a visible track record of legitimate work is a green flag. The stars themselves are not proof — they can be bought — but the shape of the account usually tells the truth.

The verdict block

Every audit ends with a single verdict block you can glance at:

### Verdict: SAFE

**Prompt injection:** Clean
**Shell exec & exfil:** Clean
**Imports:** Match purpose (requests for API calls, click for CLI)
**External URLs:** All expected (github.com, pypi.org)
**Developer:** Established (2,400 followers, 47 repos, account 6 years old)
**Repo health:** 1,200 stars, 180 forks, last push 3 days ago, MIT license

**Why this verdict:** No concerning patterns found. Developer has a long public
track record and the imports match the stated purpose of the tool.

Three possible verdicts:

• SAFE — clean across all six checks, developer has a real track record, code matches purpose. Proceed with normal caution.
• CAUTION — one or two yellow flags (new developer, unpinned deps, unusual but benign-looking imports). Safe to use with awareness; maybe sandbox first.
• AVOID — any confirmed injection payload, exfiltration pattern, obfuscation, or unscoped destructive command. Or: a brand-new anonymous account shipping a tool that wants broad permissions.

When the skill is uncertain between SAFE and CAUTION, it errs toward CAUTION. When uncertain between CAUTION and AVOID, it errs toward AVOID. Your install, your risk — false positives cost you ten seconds of re-reading, false negatives can cost you a lot more.

How it’s different from npm audit, Snyk, and Socket

Automated dependency scanners are essential and you should run them. They catch known CVEs in the packages you depend on. But CVE databases are reactive — by definition, a vulnerability has to be published before it can be caught.

Repo Safety Audit catches a different thing: intent. A malicious skill author writing fresh exfiltration code today will not appear in any CVE database, but a grep for curl | sh or base64 | eval will catch it instantly. The two checks complement each other — one finds known-bad, the other finds novel-bad. Use both.

How to install and use it

1. Install from the beginnersinai-skills marketplace in Claude Code
2. (Recommended) Run gh auth login so the audit can query GitHub’s API for developer reputation
3. Enable auto-update on the marketplace so future versions land automatically
4. Paste any GitHub URL in chat and ask: “audit this repo” or “is this safe to install?”
5. Read the verdict. Act on it.

You can also point the skill at any local path — for example, ~/.claude/skills/some-skill/ — and it will audit what’s actually on your disk. This is preferred over auditing the remote repo, because what’s installed may differ from what’s on GitHub.

Why this matters

Claude Code is on a trajectory that looks a lot like npm circa 2015: an exploding ecosystem of third-party code, easy to install, powerful permissions, minimal friction. npm went through years of painful supply-chain incidents before the community started treating code review as a default — not an exception. We don’t have to wait for Claude Code to do the same.

Most skill authors are honest. Most installs will always be fine. But the asymmetry is brutal — one compromised skill can touch every project on your machine. The cost of a two-minute audit is tiny. The cost of skipping one is occasionally catastrophic. Repo Safety Audit makes the two-minute version actually take two minutes.

Honest limitations

• Static analysis only. The skill reads code, it doesn’t execute it. A clever attacker can still slip something past grep-based checks. Treat the verdict as a strong signal, not a certificate.
• Intent, not correctness. Broken code is annoying but not dangerous. The audit focuses on malicious intent, not code quality.
• Complement, not replacement. Run this alongside npm audit, pip-audit, or Socket/Snyk for dependency-level CVE coverage.
• Point in time. An audit today doesn’t cover an update next week. Re-audit on updates.

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