AI & Agents·v0.1.0

Hook Development for Claude Code Plugins Agent Skill

This skill should be used when the user asks to "create a hook", "add a PreToolUse/PostToolUse/Stop hook", "validate tool use", "implement…

Context cost
11.3k tokensestimated from the bundle, loaded when it triggers
Bundle
11 files · 64.2 kB6 scripts among them — read before you run
Licence
not declarednone named by its author
Last change
—v0.1.0
Servers it uses
Noneruns standalone

What it does

This skill should be used when the user asks to "create a hook", "add a PreToolUse/PostToolUse/Stop hook", "validate tool use", "implement prompt-based hooks", "use ${CLAUDE_PLUGIN_ROOT}", "set up event-driven automation", "block dangerous commands", or mentions hook events (PreToolUse, PostToolUse, Stop, SubagentStop, SessionStart, SessionEnd, UserPromptSubmit, PreCompact, Notification). Provides comprehensive guidance for creating and implementing Claude Code plugin hooks with focus on advanced prompt-based hooks API.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

developer tools
Filed under

AI & Agents

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md16.2 kB · preview
--- name: hook-development version: 0.1.0 ---
7# Hook Development for Claude Code Plugins
8
9## Overview
10
11Hooks are event-driven automation scripts that execute in response to Claude Code events. Use hooks to validate operations, enforce policies, add context, and integrate external tools into workflows.
12
13**Key capabilities:**
14- Validate tool calls before execution (PreToolUse)
15- React to tool results (PostToolUse)
16- Enforce completion standards (Stop, SubagentStop)
17- Load project context (SessionStart)
18- Automate workflows across the development lifecycle
19
20## Hook Types
21
22### Prompt-Based Hooks (Recommended)
23
24Use LLM-driven decision making for context-aware validation:
25
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md2,104 words
Files11
Licencenot declared
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈150
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
11,200
on trigger
The instruction body and 10 supporting files, read only when the skill fires.
5.7%
of a 200k window
Ten skills this size would take about 57% of the window before you open a file.
050k100k150k200k context window

11.3k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

11 files, 64.2 kB on disk. Mostly text — the instructions the model reads — with 6 scripts in it that your client would run only if the instructions tell it to.

  • SKILL.md16.2 kB
  • examples/load-context.sh1.7 kB
  • examples/validate-bash.sh1.3 kB
  • examples/validate-write.sh1.2 kB
  • references/advanced.md10.1 kB
  • references/migration.md8.3 kB
  • references/patterns.md7.1 kB
  • scripts/hook-linter.sh4.2 kB
  • scripts/README.md3.7 kB
  • scripts/test-hook.sh5.3 kB
  • scripts/validate-hook-schema.sh5.1 kB
What is not in it

A skill installs nothing and depends on nothing: it is a folder your client reads. This one carries 6 scripts beside the text, so the bundle is 11 files you can review in full before installing.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Hook Development for Claude Code Plugins · 11.3k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/fazxes-hook-development-for-claude-code-plugins/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/hook-development-for-claude-code-plugins" ] && { [ ! -e .claude/skills/hook-development-for-claude-code-plugins ] || { mv .claude/skills/hook-development-for-claude-code-plugins "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/hook-development-for-claude-code-plugins" .claude/skills/ && echo "Installed .claude/skills/hook-development-for-claude-code-plugins"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add fazxes/hook-development-for-claude-code-plugins

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/hook-development-for-claude-code-plugins/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/fazxes-hook-development-for-claude-code-plugins/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/hook-development-for-claude-code-plugins" ] && { [ ! -e ~/.claude/skills/hook-development-for-claude-code-plugins ] || { mv ~/.claude/skills/hook-development-for-claude-code-plugins "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/hook-development-for-claude-code-plugins" ~/.claude/skills/ && echo "Installed ~/.claude/skills/hook-development-for-claude-code-plugins" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/hook-development-for-claude-code-plugins/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where. It appears as hook-development in Gemini CLI, Codex, Copilot and Grok (its own name); Claude Code lists it by the folder name, hook-development-for-claude-code-plugins.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Version0.1.0
Publishedno release date on file
PriceFree
Referencefazxes/hook-development-for-claude-code-plugins

Versions

v0.1.0 is what is on the shelf; no release here carries a date. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

v0.1.0
  • No earlier releases have been published to the marketplace.
Pinning

The install command always fetches the release that is current the day you run it — v0.1.0 today — and cannot ask for an earlier one. The copy on your disk does not change until you run it again.

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