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PreToolUse

PreToolUse is a hook for coding agents from ab604/claude-code-r-skills. Its token cost is not measured, scanned A, original, MIT.

A set of pre-tool checks that run before Bash, Write, or Edit actions in Claude Code. The checks warn about potentially risky Git pushes, random documentation files, and when it may be useful to compact the conversation.

In plain words
What is it for?
Use it to warn before pushing to Git, discourage scattered Markdown files, and suggest compacting context during longer work sessions.
Why use it?
It adds reminders around actions that can affect the repository or make an agent session harder to manage.

Hook

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 r-skills plugin — 8 skills, 4 commands, 3 agents, 4 hooks shipped together

One of 4 entries in hooks.json — they are configured in one file and arrive together.

not rated 198 +1 5mo ago A scan tokens not measured original MIT
View the source file ab604/claude-code-r-skills
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 ab604/claude-code-r-skills
Claude Code
/plugin install r-skills

Or install r-skills, the plugin that ships this one along with the rest of its 8 skills, 4 commands, 3 agents, 4 hooks.

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/ab604/claude-code-r-skills/pre-tool-use.svg)](https://agentmods.dev/hooks/ab604/claude-code-r-skills/pre-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/ab604/claude-code-r-skills/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/ab604/claude-code-r-skills/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 · 34 lines

What it actually says

{
  "PreToolUse": [
    {
      "matcher": "Bash",
      "hooks": [
        {
          "type": "command",
          "command": "node \"${CLAUDE_PLUGIN_ROOT}/.claude/hooks/scripts/git-push-warn.js\""
        }
      ],
      "description": "Warn before git push to prevent accidental pushes"
    },
    {
      "matcher": "Write",
      "hooks": [
        {
          "type": "command",
          "command": "node \"${CLAUDE_PLUGIN_ROOT}/.claude/hooks/scripts/doc-blocker.js\""
        }
      ],
      "description": "Warn about creating random .md files - keeps docs consolidated"
    },
    {
      "matcher": "Edit|Write",
      "hooks": [
        {
          "type": "command",
          "command": "node \"${CLAUDE_PLUGIN_ROOT}/.claude/hooks/scripts/suggest-compact.js\""
        }
      ],
      "description": "Suggest manual compaction at logical intervals"
    }
  ]
}
Same file

What else hooks.json configures

This page is one entry in a file that holds 4. Installing the file brings all of them; each is measured and scanned on its own page.

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 · 34 lines scan A 575bf8bd9467

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository ab604/claude-code-r-skills (198 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 2026-08-30.

Related

Other hooks, from other repositories

PostToolUse

Runs after a tool call finishes for Write and Edit tool calls, executing format_and_lint.sh. From supabase/supabase.

supabase/supabase · not measured

SessionStart

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

google-gemini/gemini-cli · not measured

SessionStart

Runs when a session starts on startup, executing install_pkgs.sh. From supabase/supabase.

supabase/supabase · 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

PreToolUse

Runs before the agent uses a tool, executing pre-write.sh and pre-bash.sh (2 commands). From anthropics/claude-cookbooks.

anthropics/claude-cookbooks · not measured

SessionStart

Runs when a session starts, executing session-start.sh. From anthropics/claude-cookbooks.

anthropics/claude-cookbooks · not measured