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PreToolUse

PreToolUse is a hook for Claude Code from Wishmakingfairy/vibecheck. Its token cost is not measured, scanned A, original, MIT.

A pre-action check that runs a Python security script before the agent writes, edits, or makes multiple edits to files.

In plain words
What is it for?
Use it to add a security gate to file-writing actions made with Write, Edit, or MultiEdit tools.
Why use it?
It can catch security issues before changes are written into the codebase.

Hook for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_ROOT} variable.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the vibecheck plugin — 4 skills, 1 agent, 1 hook shipped together

not rated 4 5mo ago A scan tokens not measured original MIT
View the source file Wishmakingfairy/vibecheck
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add Wishmakingfairy/vibecheck
Claude Code
/plugin install vibecheck

Made for: Claude Code.

Or install vibecheck, the plugin that ships this one along with the rest of its 4 skills, 1 agent, 1 hook.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for PreToolUse

README.md
[![agentmods](https://agentmods.dev/badge/hooks/wishmakingfairy/vibecheck/pre-tool-use.svg)](https://agentmods.dev/hooks/wishmakingfairy/vibecheck/pre-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/wishmakingfairy/vibecheck/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/wishmakingfairy/vibecheck/pre-tool-use.svg" alt="Measured on agentmods" height="20"></a>
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

PreToolUse 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 6d ago.

A static scan of the commands this hook runs, not an audit. A hook is shell that executes on your machine at the event it names, which is why every command in it is printed with what was found.

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.

hooks/hooks.json · 14 lines

What it actually says

{
  "PreToolUse": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "python3 ${CLAUDE_PLUGIN_ROOT}/hooks/security_gate.py",
          "timeout": 10000
        }
      ],
      "matcher": "Write|Edit|MultiEdit"
    }
  ]
}
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. 6d ago First seen · 14 lines scan A b6e172b3e4b6

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository Wishmakingfairy/vibecheck (4 stars, last pushed 5mo ago), licensed MIT. Its token cost is not measured: a hook is shell that never enters the context. 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 2026-08-31.

Securityai-securityapi-key-detectionclaude-codeclaude-code-plugindevsecopsowasp
Related

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SessionStart

Runs when a session starts on startup, executing session_banner.py via python3. From appsec-foundry/appsec-advisor.

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SubagentStop

Runs when a subagent finishes, executing agent_logger.py via python3. From appsec-foundry/appsec-advisor.

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SessionStart

Runs when a session starts, executing on-start.js via node. From google-gemini/gemini-cli.

google-gemini/gemini-cli · not measured

PreToolUse

Runs before the agent uses a tool for Bash tool calls, running an inline shell check. From apache/superset.

apache/superset · not measured