agentmods.dev

skarn-guard-codex

A security plugin that checks agent actions for leaked secrets, malicious package installation, and data theft.

In plain words
What is it for?
It helps protect coding-agent workflows by guarding command execution and reviewing activity for security problems.
Why use it?
It can block risky tool calls before they run and can also scan sessions and configuration files in audit mode.

Plugin for Claude Code

31 4d ago A scan tokens not measured original MIT
View the source file skarn-security/agent-guard
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.

Claude Code
/plugin marketplace add skarn-security/agent-guard
agentmods
npx agentmods add plugins/skarn-security/agent-guard/codex
Clone the repo
git clone --depth 1 https://github.com/skarn-security/agent-guard

Made for: Claude Code.

Per session not measured What this adds to a session before it is invoked.
When invoked not measured Not applicable: nothing here is loaded into a session.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Security

Grade A, and why

skarn-guard-codex 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.

codex/.claude-plugin/plugin.json · 20 lines

What it actually says

{
  "name": "skarn-guard-codex",
  "version": "0.27.0",
  "description": "Real-time pre-execution guard that blocks AI tool calls leaking a secret, installing a malicious package, or exfiltrating data, plus the skarn-audit skill (scan sessions and vet configs, redacted). Backed by the Skarn detection engine. Audit mode reports only.",
  "author": {
    "name": "Skarn",
    "url": "https://getskarn.com"
  },
  "homepage": "https://getskarn.com",
  "repository": "https://github.com/skarn-security/agent-guard",
  "license": "MIT",
  "keywords": [
    "security",
    "secrets",
    "guard",
    "skills",
    "audit"
  ]
}
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 · 20 lines scan A bf7a3dd622f2

Subscribe to this mod's changes

skarn-guard-codex is a plugin published in the GitHub repository skarn-security/agent-guard (31 stars, last pushed 4d ago), licensed MIT. Its token cost is not measured: this kind of file is read by the harness, not the model. 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.

Securitygemini-cli-extension
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