PreToolUse hooks that run before selected shell commands, such as starting development servers, installing packages, testing, building, using Docker, or running Playwright. They can block some commands and remind the agent to use tmux, a persistent terminal session.

Use them to require development servers to run inside tmux and to remind the agent about persistent sessions before long builds, installs, tests, or other commands.

They catch risky or inconvenient command patterns before execution and help keep logs available for long-running development work.

PreToolUse — Hook by codelably

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/codelably/harmony-claude-code/pre-tool-use

Clone the repo

git clone --depth 1 https://github.com/codelably/harmony-claude-code

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

PreToolUse 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 yesterday.

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

Copies of this mod

1 near-identical copy found in the catalogue:

PreToolUse — 89% identical, 18 lines differ

hooks/hooks.json · 54 lines

How it starts

The opening of the file, as written. The whole thing — 54 lines — stays where its author put it; the contents beside it link to each section on GitHub.

{
  "PreToolUse": [
    {
      "matcher": "tool == \"Bash\" && tool_input.command matches \"(npm run dev|pnpm( run)? dev|yarn dev|bun run dev)\"",
      "hooks": [
        {
          "type": "command",
          "command": "node -e \"console.error('[Hook] BLOCKED: Dev server must run in tmux for log access');console.error('[Hook] Use: tmux new-session -d -s dev \\\"npm run dev\\\"');console.error('[Hook] Then: tmux attach -t dev');process.exit(1)\""
        }
      ],
      "description": "Block dev servers outside tmux - ensures you can access logs"
    },
    {
      "matcher": "tool == \"Bash\" && tool_input.command matches \"(npm (install|test)|pnpm (install|test)|yarn (install|test)?|bun (install|test)|cargo build|make|docker|pytest|vitest|playwright)\"",
      "hooks": [
        {
          "type": "command",
          "command": "node -e \"if(!process.env.TMUX){console.error('[Hook] Consider running in tmux for session persistence');console.error('[Hook] tmux new -s dev  |  tmux attach -t dev')}\""
        }
      ],
      "description": "Reminder to use tmux for long-running commands"
    },
    {
      "matcher": "tool == \"Bash\" && tool_input.command matches \"git push\"",
      "hooks": [
        {
          "type": "command",
          "command": "node -e \"console.error('[Hook] Review changes before push...');console.error('[Hook] Continuing with push (remove this hook to add interactive review)')\""
        }
      ],
      "description": "Reminder before git push to review changes"
    },
    {
      "matcher": "tool == \"Write\" && tool_input.file_path matches \"\\\\.(md|txt)$\" && !(tool_input.file_path matches \"README\\\\.md|CLAUDE\\\\.md|AGENTS\\\\.md|CONTRIBUTING\\\\.md\")",
      "hooks": [
        {
          "type": "command",
          "command": "node -e \"const fs=require('fs');let d='';process.stdin.on('data',c=>d+=c);process.stdin.on('end',()=>{const i=JSON.parse(d);const p=i.tool_input?.file_path||'';if(/\\.(md|txt)$/.test(p)&&!/(REA

Read the full file on GitHub · 54 lines

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.

yesterday First seen · 54 lines scan A cc2d4a38e5b3

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository codelably/harmony-claude-code (42 stars, last pushed 6mo 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.

Browser automation DevOps and cloud Testing

PreToolUse

Getting it into your agent

Grade A, and why

Nothing flagged

Copies of this mod

How it starts

What this file has done since we first saw it

Other hooks, from other repositories

PostToolUse

PreToolUse

SubagentStop

PostToolUse

PostToolUse

SessionStart