hook-creator

1. Identify the use case - Determine what the hook should accomplish
2. Select the appropriate event - Choose from available hook events (see references/hook-events.md)
3. Design the hook command - Write shell command that processes JSON input from stdin
4. Configure the matcher - Set tool/event filter (use * for all, or specific tool names like Bash, Edit|Write)
5. Choose storage location - User settings (~/.claude/settings.json) or project (.claude/settings.json)
6. Test the hook - Verify behavior with a simple test case

```json

{

"hooks": {

"": [

{

"matcher": "",

"hooks": [

{

"type": "command",

"command": ""

}

]

}

]

}

}

```

Reading Input Data

Hooks receive JSON via stdin. Use jq to extract fields:

```bash

# Extract tool input field

jq -r '.tool_input.file_path'

# Extract with fallback

jq -r '.tool_input.description // "No description"'

# Conditional processing

jq -r 'if .tool_input.file_path then .tool_input.file_path else empty end'

```

Exit Codes for PreToolUse

• 0 - Allow the tool to proceed
• 2 - Block the tool and provide feedback to Claude

Matcher Patterns

• * - Match all tools
• Bash - Match only Bash tool
• Edit|Write - Match Edit or Write tools
• Read - Match Read tool

Log all bash commands:

```bash

jq -r '"\(.tool_input.command)"' >> ~/.claude/bash-log.txt

```

Auto-format TypeScript after edit:

```bash

jq -r '.tool_input.file_path' | { read f; [[ "$f" == *.ts ]] && npx prettier --write "$f"; }

```

Block edits to .env files:

```bash

python3 -c "import json,sys; p=json.load(sys.stdin).get('tool_input',{}).get('file_path',''); sys.exit(2 if '.env' in p else 0)"

```

• Hook Events Reference: See references/hook-events.md for detailed event documentation with input/output schemas
• Example Configurations: See references/examples.md for complete, tested hook configurations