PreToolUse

A pre-tool check that runs before the agent uses Bash, Read, or Glob. It can inspect commands and file paths and add instructions to the agent’s context.

In plain words
What is it for?
Use it to enforce project-specific checks before shell commands and file searches, especially when a graph.json file is available.
Why use it?
It helps guide the agent toward a required graph query before it searches or reads source files directly.

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/ggwhite/4x/pre-tool-use
Clone the repo
git clone --depth 1 https://github.com/ggwhite/4x

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 0 findings. Scan, not verified.
Origin 88% copy Near-identical to another mod 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 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.

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.

Origin

This is a copy

88% identical to PreToolUse — 2 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 · 22 lines

What it actually says

{
  "PreToolUse": [
    {
      "matcher": "Bash",
      "hooks": [
        {
          "type": "command",
          "command": "CMD=$(python3 -c \"import json,sys; d=json.load(sys.stdin); print(d.get('tool_input',d).get('command',''))\" 2>/dev/null || true); case \"$CMD\" in *grep*|*rg\\ *|*ripgrep*|*find\\ *|*fd\\ *|*ack\\ *|*ag\\ *)   [ -f graphify-out/graph.json ] &&   echo '{\"hookSpecificOutput\":{\"hookEventName\":\"PreToolUse\",\"additionalContext\":\"MANDATORY: graphify-out/graph.json exists. You MUST run `graphify query \\\"<question>\\\"` before grepping raw files. Only grep after graphify has oriented you, or to modify/debug specific lines.\"}}'   || true ;; esac"
        }
      ]
    },
    {
      "matcher": "Read|Glob",
      "hooks": [
        {
          "type": "command",
          "command": "HIT=$(python3 -c \"import json,sys;d=json.load(sys.stdin);t=d.get('tool_input',d);s=(str(t.get('file_path') or '')+' '+str(t.get('pattern') or '')+' '+str(t.get('path') or '')).lower().replace(chr(92),'/');exts=('.py','.js','.ts','.tsx','.jsx','.go','.rs','.java','.rb','.c','.h','.cpp','.hpp','.cc','.cs','.kt','.swift','.php','.scala','.lua','.sh','.md','.rst','.txt','.mdx');sys.stdout.write('1' if 'graphify-out/' not in s and any(e in s for e in exts) else '')\" 2>/dev/null || true); if [ \"$HIT\" = 1 ] && [ -f graphify-out/graph.json ]; then echo '{\"hookSpecificOutput\":{\"hookEventName\":\"PreToolUse\",\"additionalContext\":\"MANDATORY: graphify-out/graph.json exists. You MUST run graphify before reading source files. Use: `graphify query \\\"<question>\\\"` (scoped subgraph), `graphify explain \\\"<concept>\\\"`, or `graphify path \\\"<A>\\\" \\\"<B>\\\"`. Only read raw files after graphify has oriented you, or to modify/debug specific lines. This rule applies to subagents too — include it in every subagent prompt involving code exploration.\"}}'; fi || true"
        }
      ]
    }
  ]
}
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 · 22 lines scan A 300c1120c1ad

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository ggwhite/4x (33 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 0 findings. It is 88% identical to PreToolUse, differing in 2 lines, and is treated as a copy.