agentmods.dev

PostToolUse

Post-tool hooks are automatic commands that run after Write, Edit, or Bash tool calls finish. They run Agent Owl scripts to hash files or check compliance.

In plain words
What is it for?
Use them to hash files after edits and run a compliance check after shell commands.
Why use it?
They reduce the need to remember separate integrity and compliance checks after changing files or running commands.

Hook

Part of the agent-owl plugin — 1 command, 2 hooks, 1 MCP server shipped together

0 28d ago A scan tokens not measured original MIT
View the source file arnwaldn/agent-owl
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/arnwaldn/agent-owl/post-tool-use
Clone the repo
git clone --depth 1 https://github.com/arnwaldn/agent-owl

Or install agent-owl, the plugin that ships this one along with the rest of its 1 command, 2 hooks, 1 MCP server.

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

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 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 · 26 lines

What it actually says

{
  "PostToolUse": [
    {
      "matcher": "Write|Edit",
      "hooks": [
        {
          "type": "command",
          "command": "python \"${CLAUDE_PLUGIN_ROOT}/hooks/owl-post-write.py\"",
          "timeout": 10,
          "statusMessage": "Agent Owl: hashing file..."
        }
      ]
    },
    {
      "matcher": "Bash",
      "hooks": [
        {
          "type": "command",
          "command": "python \"${CLAUDE_PLUGIN_ROOT}/hooks/owl-compliance-check.py\"",
          "timeout": 15,
          "statusMessage": "Agent Owl: compliance check..."
        }
      ]
    }
  ]
}
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 · 26 lines scan A 66bda731b4e5

Subscribe to this mod's changes

PostToolUse is a hook published in the GitHub repository arnwaldn/agent-owl (0 stars, last pushed 28d 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.

auditclaude-codecomplianceeu-ai-actfile-integritymcp
Related

Other hooks, from other repositories

SessionStart

Runs when a session starts, running chainloop trace hook claude session-start. From chainloop-dev/chainloop.

chainloop-dev/chainloop · not measured

PreToolUse

Runs before the agent uses a tool for Edit, Write and Bash tool calls, executing metrics-log.sh (3 commands). From RD-DCS/venutian-antfarm.

RD-DCS/venutian-antfarm · not measured

PostToolUse

Runs after a tool call finishes for Write and Edit tool calls, executing format_and_lint.sh. From supabase/supabase.

supabase/supabase · not measured

SessionStart

Runs when a session starts, executing on-start.js via node. From google-gemini/gemini-cli.

google-gemini/gemini-cli · not measured

SessionStart

Runs when a session starts on startup, executing install_pkgs.sh. From supabase/supabase.

supabase/supabase · not measured

PreToolUse

Runs before the agent uses a tool for Bash tool calls, running an inline shell check. From apache/superset.

apache/superset · not measured