Create 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 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 ├── skills/ # Skills (subdirectories with SKILL.md) │ └── skill-name/ │ ├── SKILL.md │ └── references/ ├── agents/ # Subagent definitions (.md files) ├── .mcp.json # MCP server definitions └── README.md # Plugin documentation ```

> **Legacy `commands/` format**: Older plugins may include a `commands/` directory with single-file `.md` slash commands. This format still works, but new plugins should use `skills/*/SKILL.md` instead — the Cowork UI presents both as a single "Skills" concept, and the skills format supports progressive disclosure via `references/`.

**Rules:**

- `.claude-plugin/plugin.json` is always required - Component directories (`skills/`, `agents/`) 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`.

```json { "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):

```json { "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 | | ---------------------------------- | ------------------- | --------------------------- | | 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 | | Commands (legacy) | `commands/*.md` | Markdown + YAML frontmatter |

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 skills the most useful. **Scaffold new plugins with `skills/*/SKILL.md` — do not create `commands/` unless the user explicitly needs the legacy single-file format.**

### 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:

```markdown # Connectors

## How tool references work

Plugin files use `~~category` as a place