Checks that run before the agent uses tools such as shell commands, file edits, web requests, and database operations.

Use it to apply pre-action safeguards to commands, file changes, database migrations, web scraping, and other configured tools.

They can catch unsafe writes, hardcoded values, exposed secrets, conflicting operations, or unsuitable context before the action happens.

PreToolUse — Hook by joymin5655

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/joymin5655/agent/pre-tool-use

Clone the repo

git clone --depth 1 https://github.com/joymin5655/Agent

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 83% 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

83% identical to SessionStart — 76 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.

hooks/hooks.json · 89 lines

How it starts

The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.

{
  "PreToolUse": [
    {
      "matcher": "Bash",
      "hooks": [
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" pre-tool-guard.sh"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" loop-write-guard.py"
        }
      ]
    },
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" r4-mutex-check.sh"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" context-mode-guard.sh"
        }
      ]
    },
    {
      "matcher": "Write|Edit|MultiEdit",
      "hooks": [
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" check-hardcoding.py"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" secret-content-scan.py"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" r4-file-mutex-check.sh"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" tdd-guard.py"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" spec-gate.py"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" loop-write-guard.py"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" supervisor.py"
        },
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}/adapters/claude-code/adapter.sh\" plan-scope-allow.py"
        }

Read the full file on GitHub · 89 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.

2d ago First seen · 89 lines scan A e66b33764c19

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository joymin5655/Agent (2 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 83% identical to SessionStart, differing in 76 lines, and is treated as a copy.

LLM agent-infrastructure ai-agents claude-code devtools policy-as-code

PreToolUse

Getting it into your agent

Grade A, and why

Nothing flagged

This is a copy

How it starts

What this file has done since we first saw it

Other hooks, from other repositories

PreToolUse

SessionStart

Stop

SessionStart

PostToolUse

WorktreeCreate