PostToolUse

PostToolUse is a hook for Claude Code from Yuno15-bb/c-brain. Its token cost is not measured, scanned A, a copy of TaskCompleted, Apache-2.0.

A group of after-tool hooks that records agent activity after tools are used. Different hooks update a liveness heartbeat, track file reads, record writes, and create post-change information.

In plain words
What is it for?
Use it to run status updates after any tool call, track reads, process file changes, and generate change-related records after edits.
Why use it?
It makes session activity visible and keeps records up to date while the agent works. The heartbeat also shows whether the agent is still active.

Hook for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_ROOT} variable. Also seen: names the NotebookEdit tool.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the c-brain plugin — 3 skills, 8 agents, 5 hooks shipped together

One of 5 entries in hooks.json upstream. Installing this one merges just its entry into your config; the other 4 are separate, each on its own page.

Good fit Use it to run status updates after any tool call, track reads, process file changes, and generate change-related records after edits.

Compare 6 hooks from other repositories ↓
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add Yuno15-bb/c-brain
Claude Code
/plugin install c-brain

Made for: Claude Code.

Or install c-brain, the plugin that ships this one along with the rest of its 3 skills, 8 agents, 5 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 PostToolUse

README.md
[![agentmods](https://agentmods.dev/badge/hooks/yuno15-bb/c-brain/post-tool-use/github.svg)](https://agentmods.dev/hooks/yuno15-bb/c-brain/post-tool-use)
Your own site
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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/yuno15-bb/c-brain/post-tool-use"><img src="https://agentmods.dev/badge/hooks/yuno15-bb/c-brain/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 70% copy Near-identical to another mod 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 2mo 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.

Origin

This is a copy

70% identical to TaskCompleted — 39 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

hooks/hooks.json · 45 lines

What it actually says

{
  "PostToolUse": [
    {
      "_why": "SESSION LIVENESS. Every other PostToolUse entry matches a SLICE of the tools — Read for one, Write|Edit for the others — so a session spent in Bash, Grep or Task emitted no sign of life at all and the capsule hid the orb mid-work (measured: a status 654 s stale while the session never stopped). This one matches everything on purpose: the question is 'is Claude still working', and any tool running is the answer. It refreshes LIVENESS only, never the activity label.",
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "python3 \"${CLAUDE_PLUGIN_ROOT}/hooks/brain_status.py\" heartbeat",
          "timeout": 5
        }
      ]
    },
    {
      "matcher": "Write|Edit",
      "hooks": [
        {
          "type": "command",
          "command": "python3 \"${CLAUDE_PLUGIN_ROOT}/hooks/on_fiche_write.py\"",
          "timeout": 15
        }
      ]
    },
    {
      "matcher": "Read",
      "hooks": [
        {
          "type": "command",
          "command": "python3 \"${CLAUDE_PLUGIN_ROOT}/hooks/track_read.py\"",
          "timeout": 10
        }
      ]
    },
    {
      "matcher": "Write|Edit|MultiEdit|NotebookEdit",
      "hooks": [
        {
          "type": "command",
          "command": "python3 \"${CLAUDE_PLUGIN_ROOT}/companion/hooks/post_diff.py\"",
          "timeout": 8
        }
      ]
    }
  ]
}
Same file

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.

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. 2mo ago First seen · 45 lines scan A efa9006ff40e

Subscribe to this mod's changes

PostToolUse is a hook published in the GitHub repository Yuno15-bb/c-brain (3 stars, last pushed 2mo 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. It is 70% identical to TaskCompleted, differing in 39 lines, and is treated as a copy.