plugin-marketplace-builder

name

plugin-marketplace-builder

description

Build, validate, and deploy agent plugin marketplaces for Claude Code, Cursor, GitHub Copilot, and Codex. Use when creating plugins, scaffolding a marketplace, writing plugin manifests, configuring MCP servers within plugins, writing skills or agents for plugins, validating marketplace structure, deploying to a target platform, exploring what plugins to build, or understanding how plugin marketplaces work across platforms. Also triggers for "create a marketplace", "create a plugin", "add a plugin", "validate my marketplace", "deploy to cursor/claude/github/codex", "what plugins should I create", "plugin manifest", "marketplace.json", or "plugin structure".

Plugin Marketplace Builder

Build agent plugin marketplaces that ship to Claude Code, Cursor, GitHub Copilot, and Codex.

A plugin marketplace is a directory of plugins distributed as a git repository (or zip). Each platform reads a root marketplace.json manifest that lists available plugins. Each plugin bundles components: MCP servers, skills, agents, and optionally hooks.

Marketplace Directory Layout

my-marketplace/
├── .claude-plugin/marketplace.json       # Claude Code catalog
├── .cursor-plugin/marketplace.json       # Cursor catalog
├── .github/plugin/marketplace.json       # GitHub Copilot catalog
├── .agents/plugins/marketplace.json      # Codex catalog
└── plugins/
    └── <plugin-slug>/                    # one directory per plugin
        ├── .claude-plugin/plugin.json
        ├── .cursor-plugin/plugin.json
        ├── .codex-plugin/plugin.json
        ├── plugin.json                   # GitHub Copilot (root-level)
        ├── .mcp.json                     # MCP server definitions
        ├── skills/<name>/SKILL.md        # one dir per skill
        └── agents/<name>.md              # one file per agent

Not all targets are required. Include only the manifests for platforms you target.

Root marketplace.json

All three platforms share the same schema (location differs):

{
  "name": "my-marketplace",
  "owner": { "name": "Team Name", "email": "[e-mail]" },
  "metadata": { "description": "...", "version": "1.0.0" },
  "plugins": [
    {
      "name": "my-plugin",
      "source": "./plugins/my-plugin",
      "description": "What this plugin does",
      "version": "1.0.0",
      "category": "productivity",
      "tags": ["mcp", "automation"]
    }
  ]
}

Naming rules: all names kebab-case (^[a-z0-9]+(-[a-z0-9]+)*$), max 128 chars.

Source field by platform:

• Claude Code: "./plugins/<slug>" (relative path)
• Cursor: "<slug>" (bare slug)
• GitHub Copilot: "./plugins/<slug>" (relative path)
• Codex: { "source": "local", "path": "./plugins/<slug>" } (structured object)

Plugin Manifests (per-platform differences)

Claude Code (.claude-plugin/plugin.json):

{
  "name": "slug",
  "description": "...",
  "version": "1.0.0",
  "author": { "name": "..." }
}

Cursor (.cursor-plugin/plugin.json):

{
  "name": "slug",
  "displayName": "Human Name",
  "version": "1.0.0",
  "description": "...",
  "author": { "name": "..." }
}

GitHub Copilot (plugin.json at plugin root — not in a hidden folder):

{
  "name": "slug",
  "description": "...",
  "version": "1.0.0",
  "skills": "skills/",
  "agents": "agents/",
  "mcpServers": ".mcp.json"
}

Codex (.codex-plugin/plugin.json):

{
  "name": "slug",
  "description": "...",
  "version": "1.0.0",
  "skills": "./skills/",
  "mcpServers": "./.mcp.json"
}

GitHub Copilot and Codex require explicit component path references; Claude Code and Cursor discover components implicitly.

Plugin Components

MCP Servers (.mcp.json)

{
  "mcpServers": {
    "server-name": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@org/mcp-server"],
      "env": { "API_KEY": "${API_KEY}" }
    }
  }
}

Transport types: stdio (requires command), sse / streamable-http (requires url with http(s)://).

Skills (skills/<name>/SKILL.md)

---
name: skill-name
description: When and why to use this skill
---

Instructions for the agent...

Name: kebab-case, max 64 chars. Description: required, max 1024 chars. Each skill lives in its own subdirectory.

Agents (agents/<name>.md)

Markdown files containing agent instructions. Name: kebab-case, max 64 chars.

Hooks (platform-specific lifecycle handlers)

Claude Code: command, http, prompt, or agent handlers on events like PreToolUse, PostToolUse, Stop, SessionStart. Cursor: command or prompt handlers on events like preToolUse, postToolUse, beforeShellExecution.

Workflow

1. Create marketplace directory with root manifests and plugins/ folder
2. Add plugins — create a subdirectory per plugin with manifests and components
3. Validate — run the bundled validate-marketplace.sh script or your own checks
4. Deploy — push to git and register with the target platform

Validation

Run the bundled script (path relative to this skill directory):

bash <skill-dir>/scripts/validate-marketplace.sh /path/to/marketplace
bash <skill-dir>/scripts/validate-marketplace.sh /path/to/marketplace --verbose

Requires python3 and bash. Checks: marketplace structure, manifest validity, kebab-case naming, required fields, MCP configs, skill files.

Platform Deployment Guides

Read the platform-specific reference for deployment instructions:

• Claude Code: See references/claude-code.md — CLI /plugin marketplace add, organization web console, team .claude/settings.json config
• Cursor: See references/cursor.md — Teams/Enterprise dashboard import, distribution policies
• GitHub Copilot: See references/github-copilot.md — CLI copilot plugin marketplace add, manifest differences
• Codex: See references/codex.md — repo/personal marketplace setup, $plugin-creator skill, .agents/plugins/marketplace.json

Additional References

File	Content
references/schemas.md	Full manifest schemas, validation rules, all field definitions
references/plugin-ideas.md	Plugin categories, starter ideas, marketplace organization patterns
references/pmw-reference.md	Using Plugin Marketplace Wizard (visual editor + CLI tool) to accelerate marketplace creation

Pre-ship Checklist

• Root marketplace.json exists for each target platform in the correct location
• Each plugin directory under plugins/ uses a kebab-case slug
• Each plugin has at least one platform manifest (plugin.json)
• MCP servers in .mcp.json with valid transport config (stdio needs command, remote needs url)
• Skills in skills/<kebab-name>/SKILL.md with name and description frontmatter
• Agents in agents/<kebab-name>.md with description
• All names kebab-case, no reserved or impersonation names
• Validation passes: bash <skill-dir>/scripts/validate-marketplace.sh <marketplace-dir>