Plugins — Skills Bundled with Resources

~14 min · cowork, plugins, marketplace, extensibility

Level 0🌱 Novice

0 XP0/70 lessons0/11 achievements

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Skills, agents, and assets shipped together

Cowork plugins are packaged extensions: a folder containing a manifest, one or more Skills, optional subagents, and supporting assets. They follow the same plugin marketplace as Claude Code, so the same plugin can target both products.

The shape: plugin.json declares metadata and permissions, skills/ holds SKILL.md definitions, agents/ holds subagent markdown, assets/ holds reference files (templates, brand guidelines, checklists). When the plugin is enabled, all of its skills become callable as /skill-name; its agents become available for delegation.

Permissions in plugin.json are sandboxed: fileAccess: "working-folder" (default) or "read-only"; webFetch: false by default. A plugin can't escalate its own privileges — you grant capabilities at install.

Code

A plugin manifest·json

{
  "name": "research-toolkit",
  "version": "1.2.0",
  "description": "Deep research and synthesis for analysts",
  "author": "ada@example.com",
  "skills": ["deep-research", "synthesis", "citation-format"],
  "agents": ["research-coordinator"],
  "permissions": {
    "fileAccess": "working-folder",
    "webFetch": true
  }
}

Custom local plugin layout·text

.claude/plugins/brand-voice/
├── plugin.json
├── skills/
│   ├── brand-check/
│   │   └── SKILL.md
│   └── brand-rewrite/
│       └── SKILL.md
└── assets/
    └── brand-guidelines.md

# In Claude Desktop settings.json:
{
  "plugins": [
    { "name": "brand-voice", "source": "local",
      "path": "~/.claude/plugins/brand-voice/", "enabled": true }
  ]
}

External links

Exercise

Create a local plugin with at least one skill and one supporting asset (a template or checklist). Install it in Cowork via settings.json. Invoke the skill on real input. Note what was easier than maintaining the skill standalone.

Progress

Progress is local-only — sign in to sync across devices.

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