agentmods.dev

PreToolUse

A safety check that runs before the agent reads or changes files, using an allow-checkpoint script.

In plain words
What is it for?
Use it to guard Write, Edit, and Read operations in an agent setup.
Why use it?
It adds a review point before file operations, so those actions do not happen without the checkpoint.

Hook

2 14d ago A scan tokens not measured original MIT
View the source file thgMatajs/squirrel-mode
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/thgmatajs/squirrel-mode/pre-tool-use
Clone the repo
git clone --depth 1 https://github.com/thgMatajs/squirrel-mode
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 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.

hooks/hooks.json · 13 lines

What it actually says

{
  "PreToolUse": [
    {
      "matcher": "Write|Edit|Read",
      "hooks": [
        {
          "type": "command",
          "command": "\"${CLAUDE_PLUGIN_ROOT}\"/scripts/allow-checkpoint.sh"
        }
      ]
    }
  ]
}
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 · 13 lines scan A cbcc9d5472ae

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository thgMatajs/squirrel-mode (2 stars, last pushed 14d 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 2026-08-31.

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Related

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SessionStart

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povvo/claudikins-kernel · not measured

SessionStart

Runs when a session starts, executing cli.js via node. From Davidcreador/claude-code-branch-memory-manager.

Davidcreador/claude-code-branch-memory-manager · not measured

PreToolUse

Runs before the agent uses a tool for Write, Edit, MultiEdit, Bash, WebFetch and mcp__.* tool calls, executing privacy-check.js via node. From fedec65/bettercallclaude.

fedec65/bettercallclaude · not measured

PreToolUse

Runs before the agent uses a tool for Bash tool calls, running cil hook pre-tool-use. From hautc-it/cil.

hautc-it/cil · not measured

SubagentStart

Runs when a subagent starts, running an inline shell check. From comet-ml/opik-claude-code-plugin.

comet-ml/opik-claude-code-plugin · not measured