Agent skill

Creating Hooks

“Creates Claude Code hooks.”

— description from SKILL.md by lexler

Apache-2.0Auto-check passedAgent Workflows

Install Creating Hooks

skills CLI

$ npx skills add lexler/skill-factory --skill creating-hooks -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install lexler/skill-factory creating-hooks --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .claude/skills && cp -r skills-src/output_skills/ai/claude-code/creating-hooks .claude/skills/creating-hooks && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "creating-hooks" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/ai/claude-code/creating-hooks into .claude/skills/creating-hooks/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "creating-hooks", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/lexler/skill-factory/tree/main/output_skills/ai/claude-code/creating-hooks

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add lexler/skill-factory --skill creating-hooks -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install lexler/skill-factory creating-hooks --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .agents/skills && cp -r skills-src/output_skills/ai/claude-code/creating-hooks .agents/skills/creating-hooks && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "creating-hooks" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/ai/claude-code/creating-hooks into .agents/skills/creating-hooks/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "creating-hooks", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add lexler/skill-factory --skill creating-hooks -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install lexler/skill-factory creating-hooks --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/output_skills/ai/claude-code/creating-hooks .cursor/skills/creating-hooks && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "creating-hooks" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/ai/claude-code/creating-hooks into .cursor/skills/creating-hooks/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "creating-hooks", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/lexler/skill-factory.git --path output_skills/ai/claude-code/creating-hooks

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add lexler/skill-factory --skill creating-hooks -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install lexler/skill-factory creating-hooks --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/output_skills/ai/claude-code/creating-hooks .gemini/skills/creating-hooks && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "creating-hooks" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/ai/claude-code/creating-hooks into .gemini/skills/creating-hooks/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "creating-hooks", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install lexler/skill-factory creating-hooks

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add lexler/skill-factory --skill creating-hooks -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .github/skills && cp -r skills-src/output_skills/ai/claude-code/creating-hooks .github/skills/creating-hooks && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "creating-hooks" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/ai/claude-code/creating-hooks into .github/skills/creating-hooks/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "creating-hooks", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add lexler/skill-factory --skill creating-hooks -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install lexler/skill-factory creating-hooks --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/lexler/skill-factory.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/output_skills/ai/claude-code/creating-hooks .opencode/skills/creating-hooks && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "creating-hooks" agent skill from https://github.com/lexler/skill-factory/tree/main/output_skills/ai/claude-code/creating-hooks into .opencode/skills/creating-hooks/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "creating-hooks", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: creating-hooks
GitHub stars: 239
Token cost: ~1.3k tokens
SKILL.md length: 297 words
Files: 4 (incl. scripts, references)
Skills in repo: 25
Repo updated: Aug 26, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

SKILL.md covers Setup, What Hooks Are, Configuration and Hook Events, plus 7 more sections
Runs Python scripts from its folder; calls python

About this skill

Creating Hooks is a skill in lexler/skill-factory (239 stars). Its SKILL.md is about 1.3k tokens, with 3 other files in the folder (scripts, references). Licence: Apache-2.0.

What it can do on your machine

Read from SKILL.md and the folder at commit 8017333. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Ships 1 file in scripts/ (Python), which the agent can run.
Shell commands in SKILL.md call:
- python
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Creating Hooks loads about 1.3k tokens when it runs, and up to ~27k if it reads all its reference files. Until then it costs about 10 tokens; SKILL.md has 297 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~10
When it runs · the whole SKILL.md, loaded when a task matches: ~1.3k
With references · SKILL.md plus every file in references/, read only if the agent opens them: ~27k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from lexler/skill-factory at commit 8017333, republished under its Apache-2.0 licence (© lexler). 297 words, ~1,255 tokens.

Download SKILL.mdSave it as .claude/skills/creating-hooks/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.

name: creating-hooks
description: Creates Claude Code hooks.

STARTER_CHARACTER = 🪝

Setup

First, update the reference docs to get the latest from Anthropic:

bash

python ~/.claude/skills/creating-hooks/scripts/update-docs.py

What Hooks Are

Shell commands that execute at lifecycle points in Claude Code. Unlike prompts, hooks are deterministic—they always run when triggered.

Configuration

Hooks live in settings files:

~/.claude/settings.json - User settings (all projects)
.claude/settings.json - Project settings (shared via git)
.claude/settings.local.json - Local project settings (not committed)

json

{
  "hooks": {
    "EventName": [
      {
        "matcher": "ToolPattern",
        "hooks": [
          {
            "type": "command",
            "command": "your-command-here"
          }
        ]
      }
    ]
  }
}

Matcher: Pattern to match tool names (case-sensitive)

Exact match: Write
Regex: Edit|Write
All tools: * or omit

Environment variables:

$CLAUDE_PROJECT_DIR - Absolute path to project root
$CLAUDE_ENV_FILE - File path for persisting env vars (SessionStart only)

Hook Events

Tool events (matcher applies):

PreToolUse - Before tool executes
PostToolUse - After tool completes
PermissionRequest - Permission dialog shown

Session events:

SessionStart - Session begins/resumes (matcher: startup/resume/clear/compact)
SessionEnd - Session ends
PreCompact - Before compaction (matcher: manual/auto)

Other events:

UserPromptSubmit - User submits prompt
Stop - Agent finishes
SubagentStop - Subagent finishes
Notification - Alerts sent (matcher: notification type)

Exit Codes

0: Success. stdout shown in verbose mode. For UserPromptSubmit/SessionStart, stdout added to context.
2: Block. stderr fed to Claude as error message. Blocks the action.
Other: Non-blocking error. stderr shown to user.

JSON Output

For advanced control, return JSON to stdout with exit code 0:

json

{
  "continue": false,
  "stopReason": "Message shown when stopping"
}

PreToolUse Control

json

{
  "hookSpecificOutput": {
    "hookEventName": "PreToolUse",
    "permissionDecision": "allow",
    "permissionDecisionReason": "Auto-approved",
    "updatedInput": { "field": "modified value" }
  }
}

Decisions: "allow" (bypass permission), "deny" (block), "ask" (prompt user)

PostToolUse Feedback

json

{
  "decision": "block",
  "reason": "Explanation fed to Claude"
}

Stop/SubagentStop Control

json

{
  "decision": "block",
  "reason": "Must fix X before stopping"
}

Hook Input

Hooks receive JSON via stdin:

json

{
  "session_id": "abc123",
  "transcript_path": "/path/to/transcript.jsonl",
  "cwd": "/current/dir",
  "permission_mode": "default",
  "hook_event_name": "PreToolUse",
  "tool_name": "Write",
  "tool_input": { "file_path": "/path", "content": "..." }
}

Common Patterns

Auto-format after edit:

json

{
  "hooks": {
    "PostToolUse": [{
      "matcher": "Edit|Write",
      "hooks": [{
        "type": "command",
        "command": "jq -r '.tool_input.file_path' | xargs -I{} sh -c 'echo {} | grep -q \"\\.ts$\" && npx prettier --write {}'"
      }]
    }]
  }
}

Block dangerous commands:

json

{
  "hooks": {
    "PreToolUse": [{
      "matcher": "Bash",
      "hooks": [{
        "type": "command",
        "command": "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/validate-bash.py"
      }]
    }]
  }
}

Inject context on prompt:

json

{
  "hooks": {
    "UserPromptSubmit": [{
      "hooks": [{
        "type": "command",
        "command": "echo '[REMINDER: Follow TDD]'"
      }]
    }]
  }
}

Desktop notification:

json

{
  "hooks": {
    "Notification": [{
      "hooks": [{
        "type": "command",
        "command": "osascript -e 'display notification \"Claude needs input\" with title \"Claude Code\"'"
      }]
    }]
  }
}

Hook Scripts

For complex logic, use external scripts. UV single-file format works well:

python

#!/usr/bin/env -S uv run --script
# /// script
# dependencies = []
# requires-python = ">=3.11"
# ///

import json
import sys

data = json.load(sys.stdin)
tool_input = data.get("tool_input", {})

# Validation logic here

if should_block:
    print("Error message", file=sys.stderr)
    sys.exit(2)

sys.exit(0)

Anti-Patterns

Using exit code 2 without stderr message (Claude gets no feedback)
Forgetting to handle JSON parsing errors in scripts
Blocking without explaining why (Claude will retry the same thing)
Long-running hooks without timeout (default is 60s)
Modifying files in PreToolUse (use PostToolUse for modifications)

Reference

references/anthropic-hooks.md - Complete reference (input schemas, prompt hooks, MCP tools)
references/anthropic-hooks-guide.md - Quickstart and examples

Files

SKILL.md and 3 other files (scripts, references) in output_skills/ai/claude-code/creating-hooks of lexler/skill-factory.

SKILL.md
references/anthropic-hooks-guide.md
references/anthropic-hooks.md
scripts/update-docs.py

Open the folder on GitHubat commit 8017333

Compare with similar skills

Creating Hooks next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Creating Hooks compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Creating Hooks this skilllexler/skill-factory	239	—	~1.3k	Automated safety check: Pass	Apache-2.0	1 mo ago
Hook Development for Claude Code Pluginsanthropics/claude-plugins-official	37k	11 repos	~4.1k	Automated safety check: Notes	Apache-2.0	today
Claude Code Agent Developmentanthropics/claude-plugins-official	37k	8 repos	~2.8k	Automated safety check: Pass	Apache-2.0	today
Claude Code Skill Developer Guidediet103/claude-code-infrastructure-showcase	10k	10 repos	~3.5k	Automated safety check: Pass	MIT	2 mo ago
Plugin Settings Patternanthropics/claude-plugins-official	37k	7 repos	~3k	Automated safety check: Pass	Apache-2.0	today
MCP Integration for Pluginsanthropics/claude-plugins-official	37k	11 repos	~3.1k	Automated safety check: Pass	Apache-2.0	today

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Questions about Creating Hooks

How do I install Creating Hooks in Claude Code?

Run `npx skills add lexler/skill-factory --skill creating-hooks -a claude-code`. Or copy the skill folder (output_skills/ai/claude-code/creating-hooks in lexler/skill-factory) into .claude/skills/creating-hooks in your project. Claude Code loads it when a task matches its description.

How do I install Creating Hooks in Codex?

Run `npx skills add lexler/skill-factory --skill creating-hooks -a codex`. Or copy the skill folder (output_skills/ai/claude-code/creating-hooks in lexler/skill-factory) into .agents/skills/creating-hooks in your project. Codex loads it when a task matches its description.

Can I use Creating Hooks in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add lexler/skill-factory --skill creating-hooks -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/creating-hooks, .gemini/skills/creating-hooks, .github/skills/creating-hooks and .opencode/skills/creating-hooks in your project.

What does Creating Hooks need to run?

Going by SKILL.md and its folder, Creating Hooks needs Python for the scripts in its folder and the command-line tools its instructions call (python).

Does Creating Hooks access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Creating Hooks safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.

What licence does Creating Hooks use?

Creating Hooks is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Creating Hooks use?

About 1.3k tokens (SKILL.md is roughly 5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 26k tokens, read only when the agent opens those files.

What are the alternatives to Creating Hooks?

Skills that share tags, products or a category with Creating Hooks: Hook Development for Claude Code Plugins (anthropics/claude-plugins-official, 37k stars), Claude Code Agent Development (anthropics/claude-plugins-official, 37k stars), Claude Code Skill Developer Guide (diet103/claude-code-infrastructure-showcase, 10k stars) and Plugin Settings Pattern (anthropics/claude-plugins-official, 37k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Creating Hooks?

lexler (a GitHub user) maintains it in lexler/skill-factory, which has 239 GitHub stars. The repository holds 25 skills in this directory. The repository was last updated on August 26, 2026.

Source: lexler/skill-factory on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Creating Hooks

Facts

At a glance

About this skill

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Setup

What Hooks Are

Configuration

Hook Events

Exit Codes

JSON Output

PreToolUse Control

PostToolUse Feedback

Stop/SubagentStop Control

Hook Input

Common Patterns

Hook Scripts

Anti-Patterns

Reference

Files

Compare with similar skills

Similar skills

More from lexler/skill-factory

Related

Questions about Creating Hooks