plugin-scanner

A local security scanner for AI-agent skills, plugins, MCP servers, and related tools. It checks for prompt injection, unsafe commands, exposed secrets, and suspicious supply-chain behavior.

In plain words
What is it for?
Use it to audit a local skill, plugin, MCP server, or chosen repository before installation or use, and to validate tooling in a continuous-integration process.
Why use it?
It helps identify risks before installing or trusting third-party agent tooling, without sending the target or findings to a hosted service.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/hashgraph-online/hol-guard-plugin/plugin-scanner
Any agent
npx skills add hashgraph-online/hol-guard-plugin --skill plugin-scanner
Clone the repo
git clone --depth 1 https://github.com/hashgraph-online/hol-guard-plugin

Made for: Claude Code, Codex.

Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 677 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00038 $0.00677
Opus 5 $0.00019 $0.00338
Sonnet 5 $0.00008 $0.00135
Haiku 4.5 $0.00004 $0.00068

Measured 2d ago against content hash 0fcf63535c3b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plugin-scanner scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

distributions/wshobson-agents/skills/plugin-scanner/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Plugin Scanner

Use the open-source plugin-scanner CLI when a user asks to inspect an AI agent skill, plugin, MCP server, package, or repository before installation or use.

Scanning runs locally. Do not require an account, API key, hosted service, or remote decision endpoint, and do not send the target or findings to a hosted HOL service.

When to use this skill

Use this skill when the user asks to:

  • scan or audit a SKILL.md before installing it;
  • inspect an MCP server or agent plugin for security risks;
  • check a third-party agent repository before trusting it;
  • look for prompt injection, credential exposure, unsafe commands, or suspicious package/install behavior;
  • validate a skill or plugin repository in CI or before publishing it.

Safety rules

  • Never execute code from the target repository just to scan it.
  • Never run the target's install scripts, package lifecycle hooks, or arbitrary shell commands.
  • Never read .env files, credential stores, private keys, or unrelated user secrets.
  • Prefer scanning a local path or a repository the user has already chosen to inspect.
  • Treat scanner findings as security evidence, not a guarantee that a package is safe.
  • Ask before installing plugin-scanner if the command is not already available.
  • Do not upload the target, package names, URLs, findings, prompts, or workspace contents to a hosted service.

1. Check for the scanner

command -v plugin-scanner

If it is not installed, explain that plugin-scanner is a separate open-source CLI distribution built from the HOL Guard source repository. Install only after the user explicitly approves setup:

pipx install plugin-scanner==2.2.119

Do not assume an existing hol-guard installation also provides the scanner command. If pipx is unavailable, recommend an isolated Python CLI installation approach rather than silently modifying the user's Python environment.

2. Scan the target without executing it

For a repository or directory:

Read the full file on GitHub · 86 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 86 lines · 38 tokens per session scan A 0fcf63535c3b

Subscribe to this mod's changes

plugin-scanner is a skill published in the GitHub repository hashgraph-online/hol-guard-plugin (4 stars, last pushed 6d ago), licensed Apache-2.0. It adds 38 tokens to every session and 677 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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