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PreToolUse

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

An automated hook that runs before Bash commands and certain data-fetching tool calls. It starts a YARA-based shell script, where YARA is a rule system for matching suspicious or notable patterns.

In plain words
What is it for?
Use it to run the project’s nab YARA edge check before Bash commands and matching nab fetch operations.
Why use it?
It adds a pre-action scan at the point where selected tools are about to run. This can help enforce the project’s checks before those calls proceed.

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 nab plugin — 6 skills, 1 command, 1 hook, 1 MCP server shipped together

not rated 12repo 2d ago A scan tokens not measured original MIT

Good fit Use it to run the project’s nab YARA edge check before Bash commands and matching nab fetch operations.

Compare 6 hooks from other repositories ↓
View source ↗ MikkoParkkola/nab crates.io
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 MikkoParkkola/nab
Claude Code
/plugin install nab

Made for: Claude Code.

Or install nab, the plugin that ships this one along with the rest of its 6 skills, 1 command, 1 hook, 1 MCP server.

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/mikkoparkkola/nab/pre-tool-use.svg)](https://agentmods.dev/hooks/mikkoparkkola/nab/pre-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/mikkoparkkola/nab/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/mikkoparkkola/nab/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. A grade says what 26 rules found in the file — not that it is safe.
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 7d 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.

plugin/hooks/hooks.json · 14 lines

What it actually says

{
  "PreToolUse": [
    {
      "matcher": "Bash|mcp__.*nab.*fetch.*",
      "hooks": [
        {
          "type": "command",
          "command": "${CLAUDE_PLUGIN_ROOT}/hooks/nab-yara-edge.sh",
          "timeout": 5
        }
      ]
    }
  ]
}
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. 7d ago First seen · 14 lines scan A 53c76f772e10

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository MikkoParkkola/nab (12 stars, last pushed 2d 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 2026-08-30.

Rustanti-botclicookieshttp3passkeys
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