New Hook

New hook scaffold

Target hook name: $ARGUMENTS

Step 1 — Parse intent

From $ARGUMENTS, extract:

• hook-name: lowercase, hyphen-separated (e.g., pre-edit-backup)
• purpose: what the hook should do (if not given, ask)

If hook-name is missing, stop and ask.

Step 2 — Read current hooks

Read .claude/settings.json to understand what hooks already exist. Glob .claude/hooks/scripts/ to see existing scripts.

If a hook with the same name or same purpose already exists, stop and say so.

Before continuing, classify the request:

• If it is command allow/deny, do NOT create a hook; use /update-permissions.
• If it is behavioral guidance, do NOT create a hook; use /new-rule.
• If it needs deterministic runtime checks not expressible in permissions, continue with this hook workflow.

Step 3 — Gather information (ask all at once)

Before I write the hook, a few things:

1. **Event**: When should this hook fire?
   - PreToolUse   → before a tool runs (can block/modify)
   - PostToolUse  → after a tool runs (observe, lint, log)
   - Stop         → when Claude finishes a response
   - SessionStart → when a new session begins

2. **Matcher** (for PreToolUse/PostToolUse): Which tool(s) should trigger it?
   Examples: "Write|Edit", "Bash", "Read", "*" (all tools)
   Leave blank if this is a SessionStart or Stop hook.

3. **What it does**: Describe the behavior in plain language.
   I'll write the script — just tell me what it needs to do.

4. **Inputs needed**: Does the script need to know which file was edited?
   Which command was run? The tool output?
   (Claude Code passes the full tool context as JSON via stdin — I'll handle the parsing.)

5. **On failure**: Should a failure block Claude (exit 1) or just warn (exit 0)?
   Block = hard stop, use for critical checks.
   Warn = log and continue, use for informational hooks.

Wait for answers before proceeding.

Step 4 — Write the script

Create .claude/hooks/scripts/.sh:

#!/bin/bash
# .sh — 
# Event: 
# Matcher: 
#
# Claude Code passes hook input as JSON via stdin.
# Parse with jq — never use positional args ($1, $2).

INPUT=$(cat)

# Extract relevant fields based on event type:
# PreToolUse/PostToolUse:
#   tool_name:        which tool fired (e.g., "Edit", "Bash")
#   tool_input:       the tool's input parameters
#   tool_input.file_path: for Write/Edit hooks
#   tool_input.command:   for Bash hooks
#   tool_response:    the tool's output (PostToolUse only)
#
# Stop:
#   stop_reason: why Claude stopped

# 

exit 0

Script rules:

• Always read from stdin: INPUT=$(cat)
• Always parse with jq, never use $1 or positional args
• Keep scripts deterministic: same input → same output, no side effects beyond intended action
• Scripts are for status checks, formatters, and loggers — not for logic Claude should reason through
• Add a comment explaining what each jq extraction does
• Exit 0 unless the hook is intentionally blocking (PreToolUse guard)

Step 5 — Wire into settings.json

Read .claude/settings.json. Add the hook under the correct event key.

For PreToolUse / PostToolUse:

{
  "matcher": "",
  "hooks": [
    {
      "type": "command",
      "command": "bash .claude/hooks/scripts/.sh"
    }
  ]
}

For Stop / SessionStart:

{
  "hooks": [
    {
      "type": "command",
      "command": "bash .claude/hooks/scripts/.sh"
    }
  ]
}

Append to the existing array for that event — do not overwrite existing hooks.

If the event key doesn't exist yet in settings.json, add it at the same level as existing event keys.

Step 6 — Print summary

Created: .claude/hooks/scripts/.sh
Wired:   .claude/settings.json →  → matcher: ""
Behavior: 
On failure: 

Run a quick test:
  echo '{"tool_name":"Edit","tool_input":{"file_path":"test.md"}}' | bash .claude/hooks/scripts/.sh

Remind the user: hooks are guarantees (run every time), unlike CLAUDE.md instructions which are advisory. Keep them fast — slow hooks block every tool call.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: enbiyagoral
• Source: enbiyagoral/.claude
• License: MIT

Install and usage instructions live in the source repository linked above.