This document explains the marketplace and plugin system that enables skill discovery and loading in Claude. It covers the structure of marketplace.json, how plugins organize skills into bundles, the strict resolution mode, how skill paths resolve relative to the repo root, and the licensing boundary between the two bundles. For information about the SKILL.md format that defines individual skills, see page 2.2. For the overall architecture of how skills are loaded and executed, see page 2.1.
The marketplace.json file serves as the central registry for all skills available in a repository. It defines plugins, which are logical groupings of related skills, and provides metadata about the marketplace itself.
The marketplace file contains three primary sections:
| Field | Type | Purpose | Example |
|---|---|---|---|
name | string | Unique identifier for the marketplace | "anthropic-agent-skills" |
owner | object | Contact information for marketplace maintainer | {"name": "Keith Lazuka", "email": "..."} |
metadata | object | Descriptive information and versioning | {"description": "...", "version": "1.0.0"} |
plugins | array | List of plugin definitions | See Plugin Structure below |
Each plugin in the plugins array defines a collection of related skills:
| Field | Type | Required | Purpose |
|---|---|---|---|
name | string | Yes | Unique identifier for the plugin |
description | string | Yes | Human-readable description of plugin capabilities |
source | string | Yes | Base path for skill resolution (typically "./") |
strict | boolean | Yes | Whether to enforce strict loading rules |
skills | array | Yes | List of relative paths to skill directories |
Example Plugin Definition:
Sources: .claude-plugin/marketplace.json1-45
The following diagram illustrates how the marketplace.json organizes plugins and skills:
.claude-plugin/marketplace.json — Registry Structure
Sources: .claude-plugin/marketplace.json1-45
Skills are referenced by relative paths in the skills array. The path resolution combines the plugin's source field with the skill path to locate the SKILL.md file.
Skill Path Resolution — from marketplace.json fields to filesystem
The resolution process:
.claude-plugin/marketplace.json to extract plugin definitions.plugin.skills, treat the path as relative to the repository root (the source field "./" anchors it there).SKILL.md inside the resolved directory — this is the skill definition file.scripts/, agents/, assets/) are loaded from the same directory as needed during execution.All skill paths in this repository follow the pattern ./skills/<skill-name>, meaning every skill lives directly under the top-level skills/ directory.
Sources: .claude-plugin/marketplace.json12-43 README.md33-48
The marketplace integrates with Claude Code through the plugin system. Users register marketplaces using the /plugin marketplace add command.
Marketplace Registration and Skill Loading Flow
Sources: README.md56-63 .claude-plugin/marketplace.json1-43
A single marketplace can contain multiple plugins, each serving different purposes. The current marketplace defines two distinct plugins:
document-skills Plugin| Field | Value |
|---|---|
name | document-skills |
source | "./" |
strict | false |
| License | Source-available (not open source) |
Skills:
| Path | Capability |
|---|---|
./skills/xlsx | Excel spreadsheet processing and formula recalculation |
./skills/docx | Word document creation and editing |
./skills/pptx | PowerPoint presentation manipulation |
./skills/pdf | PDF form field extraction |
These four skills power Claude's document capabilities in production. They are source-available: published for reference, but not licensed for redistribution or reuse under an open source license.
example-skills Plugin| Field | Value |
|---|---|
name | example-skills |
source | "./" |
strict | false |
| License | Apache 2.0 |
Skills (12 total):
| Path | Category |
|---|---|
./skills/algorithmic-art | Creative & Design |
./skills/brand-guidelines | Creative & Design |
./skills/canvas-design | Creative & Design |
./skills/frontend-design | Creative & Design |
./skills/theme-factory | Creative & Design |
./skills/internal-comms | Communication |
./skills/slack-gif-creator | Communication |
./skills/doc-coauthoring | Communication |
./skills/skill-creator | Developer Tooling |
./skills/mcp-builder | Developer Tooling |
./skills/web-artifacts-builder | Developer Tooling |
./skills/webapp-testing | Developer Tooling |
These skills serve as reference implementations and are fully open source under Apache 2.0.
The strict field on each plugin controls how the plugin loader handles missing or malformed skill metadata:
strict value | Behavior |
|---|---|
true | All skills in the plugin must pass validation; a single failure prevents the entire plugin from loading. |
false | The loader attempts to load each skill independently; a malformed or missing SKILL.md in one skill does not block others. |
Both plugins in this repository use "strict": false, meaning individual skill failures are isolated rather than propagating to the entire plugin.
Sources: .claude-plugin/marketplace.json11-44 README.md17-19
The two plugin bundles have distinct licenses that reflect their different purposes:
The source-available license on document-skills means developers can read the implementations as a reference for building complex skills, but cannot redistribute or incorporate them into other products. The Apache 2.0 license on example-skills allows unrestricted use, modification, and redistribution.
Sources: README.md17-19 .claude-plugin/marketplace.json11-44
The metadata object provides version tracking and description:
The owner object identifies the marketplace maintainer:
These fields enable marketplace versioning, contact information for support, and human-readable context about the marketplace's purpose.
Sources: .claude-plugin/marketplace.json3-10
When a user mentions a skill by name, Claude performs the following discovery process:
plugin.source + skill_pathFrom User Prompt to Loaded SKILL.md
Sources: .claude-plugin/marketplace.json1-45 README.md48-50
The repository at anthropics/skills is registered as a marketplace, not a standalone plugin. This distinction is important:
marketplace.json file defining multiple pluginsUsers register the entire marketplace with:
/plugin marketplace add anthropics/skills
This makes all plugins and their skills available simultaneously. Individual plugins cannot be registered separately; the marketplace is the unit of registration.
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