A pre-action hook that runs a script before an agent uses tools such as shell commands, file editing, or external service calls. It is configured to watch selected tool-use events.

Running a JavaScript hook before matching tool calls, including Bash, file operations, notebook edits, and MCP service calls.

It provides a checkpoint before actions happen, which can be used to inspect or control tool requests. The input does not specify what checks the script performs.

PreToolUse — Hook for coding agents by rjkaes: A pre-action hook that runs a script before an…

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 rjkaes/shush

Claude Code

/plugin install shush

Or install shush, the plugin that ships this one along with the rest of its 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.

README.md

[![agentmods](https://agentmods.dev/badge/hooks/rjkaes/shush/pre-tool-use.svg)](https://agentmods.dev/hooks/rjkaes/shush/pre-tool-use)

Your own site

<a href="https://agentmods.dev/hooks/rjkaes/shush/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/rjkaes/shush/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 4d 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": [
    {
      "matcher": "Bash|Read|Write|Edit|MultiEdit|NotebookEdit|Glob|Grep|mcp__.*",
      "hooks": [
        {
          "type": "command",
          "command": "node ${CLAUDE_PLUGIN_ROOT}/hooks/pretooluse.js",
          "timeout": 10
        }
      ]
    }
  ]
}

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.

4d ago First seen · 14 lines scan A 1b4a8eba8471

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository rjkaes/shush (1 stars, last pushed 3mo ago), licensed Apache-2.0. 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.

AI Safety ai-agents claude-code claude-code-hooks claude-code-plugin command-classification

PreToolUse

Getting it into your agent

Wrote this? Show the measurements

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

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