PostToolUse

PostToolUse is a hook for Claude Code from ProjectSidewalk/SidewalkWebpage. Its token cost is not measured, scanned A, original, MIT.

An automatic check that runs after files are written or edited, looking for comments that describe what code used to do or call it by an old name.

In plain words
What is it for?
It is for checking write and edit operations and blocking changes that contain historical code explanations. Markdown files are excluded from this check.
Why use it?
It prevents changelog-style comments from being added to source code when the project rules require comments to describe only current behavior.

Hook for Claude Code

One of 3 entries in settings.json — they are configured in one file and arrive together.

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/projectsidewalk/sidewalkwebpage/post-tool-use
Clone the repo
git clone --depth 1 https://github.com/ProjectSidewalk/SidewalkWebpage

Made for: Claude Code.

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/projectsidewalk/sidewalkwebpage/post-tool-use.svg)](https://agentmods.dev/hooks/projectsidewalk/sidewalkwebpage/post-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/projectsidewalk/sidewalkwebpage/post-tool-use"><img src="https://agentmods.dev/badge/hooks/projectsidewalk/sidewalkwebpage/post-tool-use.svg" alt="Measured on agentmods" 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. 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 3d 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 · 29 lines

How it starts

The opening of the file, as written. The whole thing — 29 lines — stays where its author put it; the contents beside it link to each section on GitHub.

{
  "PostToolUse": [
    {
      "matcher": "Write|Edit",
      "hooks": [
        {
          "type": "command",
          "command": "m=$(jq -r 'if ((.tool_input.file_path // \"\") | ascii_downcase | endswith(\".md\")) then empty else [.tool_input.new_string, .tool_input.content, (.tool_input.edits[]?.new_string)] | map(select(. != null)) | .[] end' 2>/dev/null | grep -niE '(^[[:space:]]*[*#]|//).*(used to|previously|formerly|replace[sd]? the old|renamed? (to|from)|no longer|was renamed)'); if [ -n \"$m\" ]; then jq -n --arg m \"$m\" '{decision:\"block\", reason:(\"A comment in this edit reads like changelog / what-the-code-USED-TO-do narration. CLAUDE.md bans this (do not describe what code used to do; use git history). Remove the historical framing; state only the current contract. Flagged:\\n\" + $m), systemMessage:\"comment-history hook: flagged a changelog-style comment\"}'; fi",
          "statusMessage": "Checking for changelog-style comments"
        },
        {
          "type": "command",
          "command": "m=$(jq -r 'if ((.tool_input.file_path // \"\") | ascii_downcase | endswith(\".md\")) then empty else [.tool_input.new_string, .tool_input.content, (.tool_input.edits[]?.new_string)] | map(select(. != null)) | .[] end' 2>/dev/null | grep -niE '((^|[^:])//|^[[:space:]]*#)[[:space:]]*((checks? if)|((gets?|sets?|returns?) the)|((loops?|iterates?) (through|over))|((creates?|initializes?) (a|an|the))|((increments?|decrements?) the)|(calls? the)|((adds?|removes?) (a|an|the)))'); if [ -n \"$m\" ]; then jq -n --arg m \"$m\" '{decision:\"block\", reason:(\"A comment in this edit restates what the code does. CLAUDE.md requires comments to say WHY, not WHAT - identifiers already say what. Delete the comment, or rewrite it to give the reason, constraint, or non-obvious tradeoff. Only inline // and # comments are checked, so ScalaDoc/JSDoc summary lines are exempt. Flagged:\\n\" + $m), systemMessage:\"restate-comment hook: flagged a comment that restates the co

Read the full file on GitHub · 29 lines

Same file

What else settings.json configures

This page is one entry in a file that holds 3. 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. 3d ago First seen · 29 lines scan A 21699e7ac13b

Subscribe to this mod's changes

PostToolUse is a hook published in the GitHub repository ProjectSidewalk/SidewalkWebpage (104 stars, last pushed 4d 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 2026-08-30.