/create-cowork-plugin

name: create-cowork-plugin
description: "Cowork セッションでプラグインをゼロから作成するスキル。 「プラグインを作って」「プラグイン開発」「plugin作成」等のリクエストで発動。 Cowork モードで .plugin ファイルを生成。"
compatibility: Requires Cowork desktop app environment with access to the outputs directory for delivering .plugin files.
source: github.com/anthropics/knowledge-work-plugins@main
triggers:
  - create-cowork-plugin
  - プラグインを作って
  - プラグイン開発
  - plugin作成
  - プラグイン設計
  - cowork plugin

Create Cowork Plugin

Build a new plugin from scratch through guided conversation. Walk the user through discovery, planning, design, implementation, and packaging — delivering a ready-to-install `.plugin` file at the end.

Overview

A plugin is a self-contained directory that extends Claude's capabilities with commands, skills, agents, hooks, and MCP server integrations. This skill encodes the full plugin architecture and a five-phase workflow for creating one conversationally.

The process: 1. **Discovery** — understand what the user wants to build 2. **Component Planning** — determine which component types are needed 3. **Design & Clarifying Questions** — specify each component in detail 4. **Implementation** — create all plugin files 5. **Review & Package** — deliver the `.plugin` file

> **Nontechnical output**: Keep all user-facing conversation in plain language. Do not expose implementation details like file paths, directory structures, or schema fields unless the user asks. Frame everything in terms of what the plugin will do.

Plugin Architecture

Directory Structure

Every plugin follows this layout:

plugin-name/
├── .claude-plugin/
│   └── plugin.json           # Required: plugin manifest
├── commands/                 # Slash commands (.md files)
├── agents/                   # Subagent definitions (.md files)
├── skills/                   # Skills (subdirectories with SKILL.md)
│   └── skill-name/
│       ├── SKILL.md
│       └── references/
├── .mcp.json                 # MCP server definitions
└── README.md                 # Plugin documentation

**Rules:**

• `.claude-plugin/plugin.json` is always required
• Component directories (`commands/`, `agents/`, `skills/`) go at the plugin root, not inside `.claude-plugin/`
• Only create directories for components the plugin actually uses
• Use kebab-case for all directory and file names

plugin.json Manifest

Located at `.claude-plugin/plugin.json`. Minimal required field is `name`.

{
  "name": "plugin-name",
  "version": "0.1.0",
  "description": "Brief explanation of plugin purpose",
  "author": {
    "name": "Author Name"
  }
}

**Name rules:** kebab-case, lowercase with hyphens, no spaces or special characters. **Version:** semver format (MAJOR.MINOR.PATCH). Start at `0.1.0`.

Optional fields: `homepage`, `repository`, `license`, `keywords`.

Custom component paths can be specified (supplements, does not replace, auto-discovery):

{
  "commands": "./custom-commands",
  "agents": ["./agents", "./specialized-agents"],
  "hooks": "./config/hooks.json",
  "mcpServers": "./.mcp.json"
}

Component Schemas

Detailed schemas for each component type are in `references/component-schemas.md`. Summary:

| Component | Location | Format | |-----------|----------|--------| | Commands | `commands/*.md` | Markdown + YAML frontmatter | | Skills | `skills/*/SKILL.md` | Markdown + YAML frontmatter | | MCP Servers | `.mcp.json` | JSON | | Agents (uncommonly used in Cowork) | `agents/*.md` | Markdown + YAML frontmatter | | Hooks (rarely used in Cowork) | `hooks/hooks.json` | JSON |

This schema is shared with Claude Code's plugin system, but you're creating a plugin for Claude Cowork, a desktop app for doing knowledge work. Cowork users will usually find commands and skills the most useful.

Customizable plugins with `~~` placeholders

> **Do not use or ask about this pattern by default.** Only introduce `~~` placeholders if the user explicitly says they want people outside their organization to use the plugin. > You can mention this is an option if it seems like the user wants to distribute the plugin externally, but do not proactively ask about this with AskUserQuestion.

When a plugin is intended to be shared with others outside their company, it might have parts that need to be adapted to individual users. You might need to reference external tools by category rather than specific product (e.g., "project tracker" instead of "Jira"). When sharing is needed, use generic language and mark these as requiring customization with two tilde characters such as `create an issue in ~~project tracker`. If used any tool categories, write a `CONNECTORS.md` file at the plugin root to explain:

# Connectors

## How tool references work

Plugin files use `~~category` as a placeholder for whatever tool the user
connects in that category. Plugins are tool-agnostic — they describe
workflows in terms of categories rather than specific products.

## Connectors for this plugin

| Category | Placeholder | Options |
|----------|-------------|-----------------|---------------|
| Chat | `~~chat` | Slack, Microsoft Teams, Discord |
| Project tracker | `~~project tracker` | Linear, Asana, Jira |

${CLAUDE_PLUGIN_ROOT} Variable

Use `${CLAUDE_PLUGIN_ROOT}` for all intra-plugin path references in hooks and MCP configs. Never hardcode absolute paths.

Guided Workflow

When you ask the user something, use AskUserQuestion. Don't assume "industry standard" defaults are correct. Note: AskUserQuestion always includes a Skip button and a free-text input box for custom answers, so do not include `None` or `Other` as options.

Phase 1: Discovery

**Goal**: Understand what the user wants to build and why.

Ask (only what is unclear — skip questions if the user's initial request already answers them):

• What should this plugin do? What problem does it solve?
• Who will use it and in what context?
• Does it integrate with any external tools or services?
• Is there a simila