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.
npx agentmods add hooks/yuno15-bb/c-brain/pre-tool-usegit clone --depth 1 https://github.com/Yuno15-bb/c-brainWrote 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.
[](https://agentmods.dev/hooks/yuno15-bb/c-brain/pre-tool-use)<a href="https://agentmods.dev/hooks/yuno15-bb/c-brain/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/yuno15-bb/c-brain/pre-tool-use.svg" alt="Measured on agentmods" height="20"></a>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 3d 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.
What it actually says
{
"PreToolUse": [
{
"matcher": "Write|Edit|MultiEdit|NotebookEdit",
"hooks": [
{
"type": "command",
"command": "python3 \"${CLAUDE_PLUGIN_ROOT}/companion/hooks/pre_snapshot.py\"",
"timeout": 5
}
]
}
]
}What else hooks.json configures
This page is one entry in a file that holds 5. Installing the file brings all of them; each is measured and scanned on its own page.
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.
- 3d ago First seen · 14 lines scan A 11232be61a5e
PreToolUse is a hook published in the GitHub repository Yuno15-bb/c-brain (2 stars, last pushed 8d ago), licensed Apache-2.0. 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.
Other hooks, from other repositories
SessionStart
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SessionStart
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SessionEnd
Runs when a session ends, executing post.sh. From T0mSIlver/localvoxtral.
Notification
Runs when the agent sends a notification for idle_prompt and permission_prompt tool calls, executing hook.sh. From JasperSui/claude-code-iterm2-tab-status.
SessionStart
Runs when a session starts, executing world-model-session.js via node. From SaravananJaichandar/world-model-mcp.
PreToolUse
Runs before the agent uses a tool for Bash tool calls, executing pre-commit-hook.sh via bash. From daveangulo/twining-mcp.