PreToolUse

A group of checks that run before the agent uses tools such as shell commands, file edits, web searches, or file reads.

In plain words
What is it for?
Applying safety checks before tool use and protecting selected files or Git operations.
Why use it?
They detect secrets and warn about or block risky actions, including destructive commands, unsafe package-manager use, and force-pushing.

Hook for Claude Code

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 hooks/steve-magne/hookstack/pre-tool-use
Clone the repo
git clone --depth 1 https://github.com/steve-magne/hookstack

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 1 finding. Scan, not verified.
Origin 44% copy Near-identical to another mod in the catalogue.
Security

Grade A, and why

PreToolUse scanned grade A with 1 finding 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 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

"command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/block-curl-pipe-sh.mjs"
Origin

This is a copy

44% identical to SessionStart — 120 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/settings.json · 123 lines

How it starts

The opening of the file, as written. The whole thing — 123 lines — stays where its author put it; the contents beside it link to each section on GitHub.

{
  "PreToolUse": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/detect-secrets.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/block-destructive.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/enforce-package-managers.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/block-push-closed-pr.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/block-curl-pipe-sh.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/guard-force-push-any.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/warn-sudo.mjs"
        }
      ],
      "matcher": "Bash"
    },
    {
      "hooks": [
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/protect-paths.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/protect-lockfiles.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/pre-write-main-guard.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/pre-write-secret-detection.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/block-generated-paths.mjs"
        },
        {
          "type": "command",
          "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/env-gitignore-guard.mjs"
        }
      ],
      "matcher": "Write|Edit"
    },
    {
      "hooks": [
        {
          "type": "command",
          "command": "node $C

Read the full file on GitHub · 123 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 · 123 lines scan A 0b448a8f9116

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository steve-magne/hookstack (7 stars, last pushed 8d 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 1 finding (makes network calls). It is 44% identical to SessionStart, differing in 120 lines, and is treated as a copy.