A set of automatic actions that runs after the coding agent finishes a tool call. After editing or writing files, it runs checks from the project's hooks directory.

Use it to run quality-warner.js after file edits and sentinel-post.js after any tool call.

It makes selected quality and sentinel checks happen automatically after changes, instead of relying on someone to remember to run them.

PostToolUse — Hook by bop-clocktower

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/bop-clocktower/canary/post-tool-use

Clone the repo

git clone --depth 1 https://github.com/bop-clocktower/canary

Made for: Claude Code.

Or install canary, the plugin that ships this one along with the rest of its 21 skills, 13 commands, 8 agents, 4 hooks, 3 MCP servers.

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.

.claude/settings.json · 22 lines

What it actually says

{
  "PostToolUse": [
    {
      "matcher": "Edit|Write",
      "hooks": [
        {
          "type": "command",
          "command": "node \"$(git rev-parse --show-toplevel)/.harness/hooks/quality-warner.js\""
        }
      ]
    },
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "node \"$(git rev-parse --show-toplevel)/.harness/hooks/sentinel-post.js\""
        }
      ]
    }
  ]
}

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.

2d ago First seen · 22 lines scan A 30d2a23303d5

Subscribe to this mod's changes

PostToolUse is a hook published in the GitHub repository bop-clocktower/canary (4 stars, last pushed 3d 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.

PostToolUse

Getting it into your agent

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

PostToolUse

SessionStart

SessionStart

PreToolUse

PreToolUse

SessionStart