A safety hook that runs before a tool is used and calls the Gemini Safety Net check.

Use it in Gemini CLI configurations to run the specified safety command on every BeforeTool event.

It adds a safety check before tool actions are carried out.

BeforeTool — Hook for Claude Code by kenryu42/gemini-safety-net

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.

Clone the repo

git clone --depth 1 https://github.com/kenryu42/gemini-safety-net

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/hooks/kenryu42/gemini-safety-net/before-tool/github.svg)](https://agentmods.dev/hooks/kenryu42/gemini-safety-net/before-tool)

Your own site

<a href="https://agentmods.dev/hooks/kenryu42/gemini-safety-net/before-tool"><img src="https://agentmods.dev/badge/hooks/kenryu42/gemini-safety-net/before-tool/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/hooks/kenryu42/gemini-safety-net/before-tool"><img src="https://agentmods.dev/badge/hooks/kenryu42/gemini-safety-net/before-tool.svg" alt="Reviewed on agentmods" width="80" 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. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

BeforeTool 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 1mo 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 · 12 lines

What it actually says

{
  "BeforeTool": [
    {
      "hooks": [
        {
          "command": "npx -y cc-safety-net hook --gemini-cli",
          "type": "command"
        }
      ]
    }
  ]
}

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.

1mo ago First seen · 12 lines scan A 0b253b04196d

Subscribe to this mod's changes

BeforeTool is a hook published in the GitHub repository kenryu42/gemini-safety-net (2 stars, last pushed 18d 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.

Security extensions gemini gemini-cli hooks safety-net

BeforeTool

Getting it into your agent

Wrote this? Show the measurements

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

Other hooks, from other repositories

SessionStart

SessionEnd

BeforeAgent

AfterAgent

AfterAgent

AfterAgent