Claude Code Plugin Marketplace

Guide for creating, validating, and managing plugin marketplaces for Claude Code. Includes schema validation, best practices, and automated tools.

When to Use This Skill

Activate this skill when:

• Creating or editing .claude-plugin/marketplace.json files
• Validating marketplace schema compliance
• Setting up plugin repositories with marketplaces
• Troubleshooting marketplace configuration issues
• Converting plugin structures to marketplace format
• Creating plugin entries with advanced features

Marketplace Schema Overview

Required Structure

All marketplaces must be located at .claude-plugin/marketplace.json in the repository root.

Required Fields:

• name: Marketplace identifier (kebab-case, lowercase alphanumeric and hyphens only)
• owner: Object with maintainer details (name required, email optional)
• plugins: Array of plugin definitions (can be empty)

Optional Metadata:

• metadata.description: Summary of marketplace purpose
• metadata.version: Marketplace version tracking (semantic versioning recommended)
• metadata.pluginRoot: Base directory for relative plugin source paths

Plugin Entry Schema

IMPORTANT: Schema Relationship

Plugin entries use the plugin manifest schema with all fields made optional, plus marketplace-specific fields (source, strict, category, tags). This means any field valid in a plugin.json file can also be used in a marketplace entry.

• When strict: false, the marketplace entry serves as the complete plugin manifest if no plugin.json exists
• When strict: true (default), marketplace fields supplement the plugin's own manifest file

Each plugin entry in the plugins array requires:

Mandatory:

• name: Plugin identifier (kebab-case)
• source: Location specification (string path or object)

Standard Metadata:

• description: Brief explanation of plugin functionality
• version: Semantic version number
• author: Creator information (object with name, optional email)
• homepage: Documentation or project URL
• repository: Source control URL
• license: SPDX license identifier (e.g., MIT, Apache-2.0)
• keywords: Array of discovery and categorization tags
• category: Organizational grouping
• tags: Additional searchability terms

Component Configuration:

• commands: Custom paths to command files or directories
• agents: Custom paths to agent files
• hooks: Custom hooks configuration or path to hooks file
• mcpServers: MCP server configurations or path to MCP config
• skills: Array of skill directory paths

Strict Mode Control:

• strict: Boolean (default: true)
  • true: Plugin must include plugin.json; marketplace fields supplement it
  • false: Marketplace entry serves as complete manifest (no plugin.json needed)

Dependencies:

• dependencies: Array of plugin names this plugin depends on (format: "namespace:plugin-name")

Plugin Source Formats

Relative Path

"source": "./plugins/my-plugin"

Relative Path with pluginRoot

// In marketplace metadata
"metadata": {
  "pluginRoot": "./plugins"
}

// In plugin entry
"source": "my-plugin"  // Resolves to ./plugins/my-plugin

GitHub Repository

"source": {
  "source": "github",
  "repo": "owner/plugin-repo",
  "path": "optional/subdirectory",
  "branch": "main"
}

Git URL

"source": {
  "source": "url",
  "url": "https://gitlab.com/team/plugin.git",
  "branch": "main"
}

Environment Variables

Use ${CLAUDE_PLUGIN_ROOT} in paths to reference the plugin's installation directory:

{
  "skills": [
    "${CLAUDE_PLUGIN_ROOT}/skills/my-skill"
  ],
  "commands": [
    "${CLAUDE_PLUGIN_ROOT}/commands"
  ]
}

This ensures paths work correctly regardless of installation location.

Advanced Plugin Entry Features

Inline Plugin Definitions

Use strict: false to define complete plugin manifests inline without requiring plugin.json:

{
  "name": "my-plugin",
  "source": "./plugins/my-plugin",
  "strict": false,
  "description": "Complete plugin definition inline",
  "version": "1.0.0",
  "author": {
    "name": "Developer Name"
  },
  "skills": [
    "${CLAUDE_PLUGIN_ROOT}/skills/skill-one",
    "${CLAUDE_PLUGIN_ROOT}/skills/skill-two"
  ]
}

Component Path Override

Customize component locations:

{
  "name": "custom-paths",
  "source": "./plugins/custom",
  "strict": false,
  "commands": ["${CLAUDE_PLUGIN_ROOT}/custom-commands"],
  "agents": ["${CLAUDE_PLUGIN_ROOT}/custom-agents"],
  "hooks": {
    "onInstall": "${CLAUDE_PLUGIN_ROOT}/hooks/install.sh"
  },
  "mcpServers": "${CLAUDE_PLUGIN_ROOT}/mcp-config.json"
}

Metadata Supplementation

With strict: true, marketplace entries can add metadata not in plugin.json:

{
  "name": "existing-plugin",
  "source": "./plugins/existing",
  "strict": true,
  "category": "development",
  "keywords": ["added", "from", "marketplace"],
  "homepage": "https://docs.example.com"
}

Validation Workflow

1. Schema Validation

Use the provided Nushell script to validate marketplace.json:

nu ${CLAUDE_PLUGIN_ROOT}/scripts/validate-marketplace.nu .claude-plugin/marketplace.json

This validates:

• JSON syntax
• Required fields presence
• Kebab-case naming
• Field type correctness
• Source path accessibility (for relative paths)

2. Plugin Entry Validation

Validate individual plugin entries:

nu ${CLAUDE_PLUGIN_ROOT}/scripts/validate-plugin-entry.nu .claude-plugin/marketplace.json "plugin-name"

Checks:

• Required fields (name, source)
• Strict mode consistency
• Dependency references
• Path validity
• Component configuration

3. Dependency Graph Validation

Check for circular dependencies and missing dependencies:

nu ${CLAUDE_PLUGIN_ROOT}/scripts/validate-dependencies.nu .claude-plugin/marketplace.json

Best Practices

Naming Conventions

• Marketplace name: Use your GitHub username or organization (e.g., vinnie357)
• Plugin names: Use descriptive kebab-case (e.g., elixir-phoenix, rust-tools, core-skills)
• Categories: Standardize on common categories: development, language, tools, frontend, backend, meta

Versioning Strategy

• Use semantic versioning for both marketplace and plugins
• Bump marketplace version when adding/removing plugins
• Bump plugin versions when updating skills or configuration
• Document breaking changes in plugin descriptions

Dependency Management

• Always declare dependencies for plugins that require other plugins
• Keep dependency chains shallow (avoid deep nesting)
• Consider creating a meta-plugin (like all-skills) that bundles related plugins
• Use namespace prefixes for dependencies (e.g., all-skills:core)

Strict Mode Decision

Use strict: false when:

• Creating simple, self-contained plugins
• All configuration is in marketplace.json
• You want centralized management
• Plugin is unlikely to be distributed independently

Use strict: true when:

• Plugin has complex configuration
• Plugin may be distributed separately
• Plugin has its own versioning lifecycle
• You want to supplement existing plugin.json with marketplace metadata

Source Path Organization

{
  "metadata": {
    "pluginRoot": "./plugins"
  },
  "plugins": [
    {
      "name": "core",
      "source": "core"  // Resolves to ./plugins/core
    },
    {
      "name": "external",
      "source": {
        "source": "github",
        "repo": "org/repo"
      }
    }
  ]
}

Common Validation Errors

Error: Invalid kebab-case name

// ❌ Invalid
"name": "myPlugin"
"name": "my_plugin"
"name": "My-Plugin"

// ✅ Valid
"name": "my-plugin"
"name": "core-skills"

Error: Missing required owner field

// ❌ Invalid
{
  "name": "marketplace"
}

// ✅ Valid
{
  "name": "marketplace",
  "owner": {
    "name": "Developer Name"
  }
}

Error: Invalid source path

// ❌ Invalid (path doesn't exist)
"source": "./plugins/nonexistent"

// ✅ Valid (path exists)
"source": "./plugins/core"

Error: Circular dependencies

// ❌ Invalid
{
  "plugins": [
    {
      "name": "plugin-a",
      "dependencies": ["namespace:plugin-b"]
    },
    {
      "name": "plugin-b",
      "dependencies": ["namespace:plugin-a"]
    }
  ]
}

Creating a New Marketplace

Step 1: Initialize Structure

mkdir -p .claude-plugin

Step 2: Create Marketplace File

Use the validation script to generate a template:

nu ${CLAUDE_PLUGIN_ROOT}/scripts/init-marketplace.nu

This creates .claude-plugin/marketplace.json with required fields.

Step 3: Add Plugin Entries

For each plugin, decide on strict mode and add entry:

{
  "name": "marketplace-name",
  "owner": {
    "name": "Your Name",
    "email": "you@example.com"
  },
  "metadata": {
    "description": "Your marketplace description",
    "version": "1.0.0",
    "pluginRoot": "./plugins"
  },
  "plugins": [
    {
      "name": "plugin-name",
      "source": "plugin-name",
      "strict": false,
      "description": "Plugin description",
      "version": "1.0.0",
      "author": {
        "name": "Your Name"
      },
      "license": "MIT",
      "category": "development",
      "skills": [
        "${CLAUDE_PLUGIN_ROOT}/skills/skill-one"
      ]
    }
  ]
}

Step 4: Validate

nu ${CLAUDE_PLUGIN_ROOT}/scripts/validate-marketplace.nu .claude-plugin/marketplace.json

Step 5: Test Installation

claude-code install ./

Migrating Existing Plugins

From Individual Plugins to Marketplace

1. Identify plugins: List all plugin.json files
2. Decide on strict mode: Choose per plugin based on complexity
3. Create marketplace.json: Add all plugins with appropriate configuration
4. Test each plugin: Verify installation works correctly
5. Document dependencies: Add dependency arrays where needed

Migration Script

Use the provided script to analyze existing structure:

nu ${CLAUDE_PLUGIN_ROOT}/scripts/analyze-plugins.nu .

This scans for plugin.json files and suggests marketplace.json structure.

Troubleshooting

Plugin Not Found After Installation

• Verify source path is correct
• Check pluginRoot in metadata if using relative paths
• Ensure plugin directory exists at specified location

Skills Not Loading

• Verify skill paths use ${CLAUDE_PLUGIN_ROOT} if needed
• Check that skill directories contain SKILL.md files
• Validate skill paths in plugin entry or plugin.json

Dependency Resolution Fails

• Ensure dependency names match exactly (including namespace)
• Check that all dependencies are listed in marketplace
• Verify no circular dependencies exist

Validation Errors

Run validation script with verbose mode:

nu ${CLAUDE_PLUGIN_ROOT}/scripts/validate-marketplace.nu .claude-plugin/marketplace.json --verbose

References

For detailed schema specifications and examples, see:

• references/schema-specification.md: Complete JSON schema
• references/examples.md: Real-world marketplace examples
• references/migration-guide.md: Step-by-step migration instructions

Script Usage

All validation and utility scripts are located in scripts/:

• validate-marketplace.nu: Full marketplace validation
• validate-plugin-entry.nu: Individual plugin entry validation
• validate-dependencies.nu: Dependency graph validation
• init-marketplace.nu: Generate marketplace template
• analyze-plugins.nu: Analyze existing plugin structure
• format-marketplace.nu: Format and sort marketplace.json

Execute scripts with:

nu ${CLAUDE_PLUGIN_ROOT}/scripts/[script-name].nu [args]