PostToolUse

PostToolUse is a hook for Claude Code from wkusnierczyk/aigent. Its token cost is not measured, scanned A, original, Apache-2.0.

An automatic check that runs after files are written or edited, but only when the changed file is named SKILL.md.

In plain words
What is it for?
It checks whether the required validation tools are installed and, when they are, validates the folder containing the changed skill file.
Why use it?
It catches problems in skill files without requiring a separate manual validation step.

Hook for Claude Code

Written for Claude Code: PostToolUse hook event.

Part of the aigent plugin — 3 skills, 1 hook shipped together

Good fit It checks whether the required validation tools are installed and, when they are, validates the folder containing the changed skill file.

Compare 6 hooks from other repositories ↓
Install with agentmods
npx agentmods add hooks/wkusnierczyk/aigent/post-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/wkusnierczyk/aigent

Made for: Claude Code.

Or install aigent, the plugin that ships this one along with the rest of its 3 skills, 1 hook.

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 PostToolUse

README.md
[![agentmods](https://agentmods.dev/badge/hooks/wkusnierczyk/aigent/post-tool-use/github.svg)](https://agentmods.dev/hooks/wkusnierczyk/aigent/post-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/wkusnierczyk/aigent/post-tool-use"><img src="https://agentmods.dev/badge/hooks/wkusnierczyk/aigent/post-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 PostToolUse

Your own site · 80×15
<a href="https://agentmods.dev/hooks/wkusnierczyk/aigent/post-tool-use"><img src="https://agentmods.dev/badge/hooks/wkusnierczyk/aigent/post-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

PostToolUse 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 · 13 lines

What it actually says

{
  "PostToolUse": [
    {
      "matcher": "Write|Edit",
      "hooks": [
        {
          "type": "command",
          "command": "command -v jq >/dev/null 2>&1 || exit 0; file=\"$(jq -r '.tool_input.file_path // empty')\" && [ -n \"$file\" ] && echo \"$file\" | grep -q 'SKILL\\.md$' && command -v aigent >/dev/null 2>&1 && aigent validate \"$(dirname \"$file\")\" 2>&1 || true"
        }
      ]
    }
  ]
}
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. 1mo ago First seen · 13 lines scan A 77cca3b1294d

Subscribe to this mod's changes

PostToolUse is a hook published in the GitHub repository wkusnierczyk/aigent (4 stars, last pushed 7mo 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.