Agent skill
setup-hooks
Set up common Claude Code hooks - auto-formatting after edits, blocking dangerous commands, and notifications. Interactive setup for your project.
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/setup-hooks
SKILL.md
Setup Hooks
Configure Claude Code hooks for your project. Hooks are deterministic automation that runs before or after Claude's tool calls.
Usage
/setup-hooks
Background
Claude Code supports these hook events:
- PreToolUse: Runs BEFORE a tool call. Can block the call.
- PostToolUse: Runs AFTER a tool call completes.
- Notification: Runs when Claude sends a notification.
- Stop: Runs when Claude finishes its turn.
Hooks are configured in .claude/settings.json under the hooks key.
Procedure
Step 1: Present Hook Options
Show the user available hook patterns:
Which hooks would you like to set up?
1. Auto-format after edits — Runs your formatter after every file edit
2. Block dangerous commands — Prevents rm -rf, git push --force, etc.
3. Lint on save — Runs your linter after every file write
4. Custom hook — Define your own
Select one or more (e.g., "1,2"):
Step 2: Configure Selected Hooks
Hook 1: Auto-Format After Edits
- Detect the project's formatter (see detection logic below)
- Create a PostToolUse hook for the
EditandWritetools:
{
"hooks": {
"PostToolUse": [
{
"matcher": "Edit|Write",
"command": "[formatter-command] $CLAUDE_FILE_PATH",
"timeout": 10000
}
]
}
}
Formatter detection:
- Node.js: Check for
prettier→npx prettier --write - Node.js: Check for
biome→npx biome format --write - Python: Check for
ruff→ruff format - Python: Check for
black→black - Rust:
cargo fmt -- - Go:
gofmt -w
Hook 2: Block Dangerous Commands
Create a PreToolUse hook for the Bash tool:
{
"hooks": {
"PreToolUse": [
{
"matcher": "Bash",
"command": "node .claude/hooks/block-dangerous.js",
"timeout": 5000
}
]
}
}
Create the blocking script at .claude/hooks/block-dangerous.js:
// Block dangerous commands in Claude Code
// Reads tool input from stdin, exits non-zero to block
const fs = require('fs');
const input = JSON.parse(fs.readFileSync('/dev/stdin', 'utf8'));
const cmd = input.tool_input?.command || '';
const BLOCKED_PATTERNS = [
/rm\s+-rf\s+[\/~]/, // rm -rf with absolute or home path
/git\s+push\s+.*--force/, // force push
/git\s+reset\s+--hard/, // hard reset
/drop\s+table/i, // SQL drop table
/drop\s+database/i, // SQL drop database
/>\s*\/dev\/sd/, // writing to block devices
/mkfs\./, // formatting filesystems
/dd\s+if=/, // disk destroyer
];
for (const pattern of BLOCKED_PATTERNS) {
if (pattern.test(cmd)) {
console.error(`BLOCKED: Command matches dangerous pattern: ${pattern}`);
process.exit(1);
}
}
process.exit(0);
Note for Windows: The script above uses Unix conventions. On Windows, adjust stdin reading:
const input = JSON.parse(require('fs').readFileSync(0, 'utf8'));
Hook 3: Lint on Save
Similar to auto-format, but runs the linter:
{
"hooks": {
"PostToolUse": [
{
"matcher": "Write",
"command": "[lint-command] $CLAUDE_FILE_PATH",
"timeout": 15000
}
]
}
}
Step 3: Install Hooks
- Read the current
.claude/settings.json - Merge the new hooks into the existing configuration (don't overwrite existing hooks)
- Write the updated settings file
- If the dangerous-command hook was selected, create the
.claude/hooks/directory and script
Step 4: Verify
Tell the user the hooks are installed and how to test them:
Hooks installed successfully!
To verify:
- Auto-format: Edit any file and check it gets formatted
- Block dangerous: Try running `rm -rf /` (it will be blocked)
- Lint on save: Write a file and check for lint output
To view all hooks: /hooks
To disable: Remove the hook entry from .claude/settings.json
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