Claude Code Plugins

Claude Code Plugins

A plugin is a self-contained directory containing skills, agents, hooks, MCP servers, or LSP servers that extends Claude Code with custom functionality shareable across projects and teams.

Plugin Structure

my-plugin/
├── .claude-plugin/
│   ├── plugin.json              # [Required] Plugin manifest
│   └── marketplace.json         # [If hosting a marketplace] Lists plugins
├── skills/                      # Skills: subdirs with SKILL.md
├── agents/                      # Custom agent definitions (markdown)
├── hooks.json                   # Hook definitions (at plugin root)
├── .mcp.json                    # MCP server configs
├── .lsp.json                    # LSP server configs
├── monitors/monitors.json       # Background monitor definitions
├── bin/                         # Executables added to Bash PATH
├── settings.json                # Default settings when plugin enabled
└── [README.md, LICENSE]

Critical: Only plugin.json and optionally marketplace.json go inside .claude-plugin/. Directories like skills/, agents/, hooks.json live at plugin root.

Plugin Manifest (plugin.json)

{
  "name": "my-plugin",
  "description": "What the plugin does; shown in plugin manager",
  "version": "1.0.0",
  "author": {
    "name": "Your Name",
    "email": "you@example.com",
    "url": "https://github.com/you"
  },
  "homepage": "https://...",
  "repository": "https://...",
  "license": "MIT",
  "keywords": ["tag1", "tag2"]
}

Fields:

• name: unique identifier + skill namespace. Skills use /{name}:{skill-name} format.
• description: required; shown in plugin manager; max ~1024 chars.
• version: optional; if omitted, git commit SHA used (every commit = new version). If set, users only receive updates on version bump.
• author, homepage, repository, license, keywords: optional metadata.

Marketplaces

A marketplace is a directory or git repo containing a .claude-plugin/marketplace.json that lists plugins. Users install plugins from marketplaces.

marketplace.json Schema

{
  "name": "my-marketplace",
  "owner": { "name": "...", "url": "..." },
  "metadata": { "description": "..." },
  "plugins": [
    {
      "name": "plugin-name",
      "description": "...",
      "version": "1.0.0",
      "author": { "name": "...", "url": "..." },
      "source": "./plugins/plugin-name/" or "./",
      "category": "productivity",
      "homepage": "https://...",
      "tags": ["tag1"]
    }
  ]
}

• source: path relative to marketplace root (./ = marketplace root is the plugin, ./plugins/name/ = subdirectory), or a git URL in known_marketplaces.
• Relative paths work for file, git, and directory sources only.

Marketplace Sources (settings.json)

{
  "github": {
    "source": "github",
    "repo": "username/repo"
  },
  "git-url": {
    "source": "git",
    "url": "https://github.com/username/repo.git"
  },
  "local": {
    "source": "directory",
    "path": "/absolute/path/to/marketplace"
  }
}

• GitHub: clones to ~/.claude/plugins/marketplaces/{name}/; plugin sources are relative paths into the clone.
• Git URL: same as GitHub; use for non-GitHub git hosts.
• Directory: local filesystem path; direct access without cloning.

Skills in Plugins

Skills live in skills/<name>/SKILL.md. Each skill becomes /plugin-name:skill-name.

SKILL.md frontmatter:

---
name: hello
description: "What the skill does. Use when [context]."
disable-model-invocation: true
allowed-tools: Bash, Read, Write
---

Skill instructions. Reference $ARGUMENTS for user input.

Reference files: Store supporting files in references/ subdirectory; include in SKILL.md as `references/file.md` or inline with @./references/file.json.

Agents in Plugins

Custom agents live in agents/ as markdown files:

plugins/my-plugin/agents/my-reviewer.md

Format:

---
name: my-reviewer
tier: sonnet
description: "What the agent does"
---

You are a code reviewer focused on security and performance...

Agents are invoked via the Agent tool using bare name (not namespaced). Plugin agents appear in /agents UI but are addressed by bare name in tool calls.

Hooks

Create hooks.json at plugin root:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Write|Edit",
        "hooks": [
          {
            "type": "command",
            "command": "npm run lint:fix",
            "timeout": 60,
            "statusMessage": "Running linter..."
          }
        ]
      }
    ],
    "PostToolUse": [...],
    "Stop": [...]
  }
}

Events: PreToolUse (before tool runs), PostToolUse (after tool completes), Stop (session ends). Matcher: regex pattern matching tool names (e.g., Write|Edit|Bash). Command: runs via shell; receives hook input as JSON on stdin. Use ${CLAUDE_PLUGIN_ROOT} to reference plugin directory.

CLI Commands

# Create plugin scaffold in ~/.claude/skills/
claude plugin init <plugin-name>

# Test local plugin during development
claude --plugin-dir ./my-plugin
# Or multiple:
claude --plugin-dir ./plugin-one --plugin-dir ./plugin-two

# Test plugin from .zip archive (v2.1.128+)
claude --plugin-dir ./my-plugin.zip

# Test from hosted URL
claude --plugin-url https://example.com/my-plugin.zip

# Reload plugins, skills, agents, hooks in current session
/reload-plugins

# List installed plugins
/plugins

# Browse and search marketplaces
/plugin marketplace browse

# Add marketplace
claude plugin marketplace add github:username/repo
claude plugin marketplace add https://git-url.git
claude plugin marketplace add /path/to/local/dir

# Install plugin from marketplace
claude plugin install <plugin-name>@<marketplace-name>

# Remove plugin
claude plugin uninstall <plugin-name>@<marketplace-name>

# Enable/disable plugin
claude plugin enable <plugin-name>@<marketplace-name>
claude plugin disable <plugin-name>@<marketplace-name>

# Validate plugin structure and manifest
claude plugin validate

Skills-Directory Plugins

Plugins in ~/.claude/skills/ auto-load without marketplace install:

claude plugin init my-local-plugin
# Creates ~/.claude/skills/my-local-plugin/
# Auto-loads as my-local-plugin@skills-dir

MCP Servers in Plugins

Configure MCP servers in .mcp.json at plugin root:

{
  "my-server": {
    "command": "node",
    "args": ["./mcp/server.js"],
    "env": { "API_KEY": "${env:MY_API_KEY}" }
  }
}

Server starts automatically when plugin is active. Use ${env:VAR} for environment variable substitution.

LSP Servers in Plugins

Configure LSP servers in .lsp.json at plugin root:

{
  "go": {
    "command": "gopls",
    "args": ["serve"],
    "extensionToLanguage": { ".go": "go" }
  }
}

Language server binary must be installed on user's machine.

When to Use Plugins vs Standalone Config

Publishing to Community Marketplace

1. Set version in plugin.json or rely on git commit SHA.
2. Host repo with .claude-plugin/plugin.json and components at root.
3. Submit via claude.ai/settings/plugins/submit or platform.claude.com/plugins/submit.
4. Run claude plugin validate before submitting.
5. Approved plugins pin to commit SHA in anthropics/claude-plugins-community.
6. Official marketplace (claude-plugins-official) is curated separately; no application process.

Converting Standalone Config to Plugin

1. Create plugin-name/.claude-plugin/plugin.json with manifest.
2. Copy ~/.claude/skills/* → plugin-name/skills/; copy ~/.claude/commands/* → plugin-name/commands/ (legacy).
3. Convert hooks from settings.json to plugin-name/hooks.json.
4. Test with claude --plugin-dir ./plugin-name.
5. Distribute via marketplace or .zip.