PreToolUse

PreToolUse is a hook for Claude Code from uqeu/estelle-cli. Its token cost is not measured, scanned A, original, Apache-2.0.

A pre-tool hook runs a command before the coding agent uses a selected tool. This setup grounds Write and Edit actions, and guards Bash commands.

In plain words
What is it for?
It helps inspect file writes, file edits, and Bash commands before they are executed.
Why use it?
It adds checks before the agent changes files or runs shell commands, reducing the chance of unsupported edits or unsafe command use.

Hook for Claude Code

Written for Claude Code: PreToolUse hook event.

Part of the estelle plugin — 26 skills, 4 agents, 9 hooks shipped together

One of 9 entries in hooks.json upstream. Installing this one merges just its entry into your config; the other 8 are separate, each on its own page.

Good fit It helps inspect file writes, file edits, and Bash commands before they are executed.

Compare 6 hooks from other repositories ↓
Install with agentmods
npx agentmods add hooks/uqeu/estelle-cli/pre-tool-use
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/uqeu/estelle-cli

Made for: Claude Code.

Or install estelle, the plugin that ships this one along with the rest of its 26 skills, 4 agents, 9 hooks.

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.

agentmods badge for PreToolUse

README.md
[![agentmods](https://agentmods.dev/badge/hooks/uqeu/estelle-cli/pre-tool-use/github.svg)](https://agentmods.dev/hooks/uqeu/estelle-cli/pre-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/uqeu/estelle-cli/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/uqeu/estelle-cli/pre-tool-use/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.

agentmods 80×15 button for PreToolUse

Your own site · 80×15
<a href="https://agentmods.dev/hooks/uqeu/estelle-cli/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/uqeu/estelle-cli/pre-tool-use.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

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 27d 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.

estelle-plugin/hooks/hooks.json · 37 lines

What it actually says

{
  "PreToolUse": [
    {
      "matcher": "Write|Edit",
      "hooks": [
        {
          "type": "command",
          "command": "npx -y --package=@fatelabs/estelle@latest -- estelle hook ground",
          "timeout": 30,
          "statusMessage": "Estelle hook ground"
        }
      ]
    },
    {
      "matcher": "Bash",
      "hooks": [
        {
          "type": "command",
          "command": "npx -y --package=@fatelabs/estelle@latest -- estelle hook guard",
          "timeout": 10,
          "statusMessage": "Estelle hook guard"
        }
      ]
    },
    {
      "matcher": "Read|Grep|Glob",
      "hooks": [
        {
          "type": "command",
          "command": "npx -y --package=@fatelabs/estelle@latest -- estelle hook pull",
          "timeout": 5,
          "statusMessage": "Estelle hook pull"
        }
      ]
    }
  ]
}
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. 27d ago Changed · +11 lines a9ddb0f806b1
  2. 1mo ago Changed 9a85b30c558d
  3. 1mo ago Changed 665a0c3d2474
  4. 1mo ago First seen · 26 lines scan A e3a396e7a354

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository uqeu/estelle-cli (0 stars, last pushed 14d 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.