How to Install Plugins for Claude Cowork: Complete Installation Guide

To install plugins for Claude Cowork, visit the web-based plugin store at claude.com/plugins, browse the available community extensions, and click "Install" to add them to your environment.

The anthropics/claude-plugins-community repository serves as the official registry for Claude Cowork extensions, maintaining a read-only mirror of the plugin marketplace that the web UI consumes to display available tools.

Understanding the Plugin Architecture

The Claude Cowork plugin system relies on a structured manifest system that separates the marketplace index from individual plugin definitions.

The Marketplace Manifest

At the root of the repository, the hidden file .claude-plugin/marketplace.json functions as the central registry. This JSON file is generated nightly by Anthropic's internal pipeline and contains metadata for every approved community plugin, including names, descriptions, and SHA hashes. When you open the Claude Cowork plugin store, the front-end fetches this manifest to render the catalog.

Individual Plugin Packages

Each plugin resides in its own subdirectory (for example, tres-finance-plugin/ or testdino/) and contains a .claude-plugin/plugin.json file. This configuration file defines the skill set, required permissions, and runtime assets specific to that extension. The marketplace manifest points to these individual plugin definitions, creating a decoupled architecture where the UI can reference static metadata while loading detailed configurations on demand.

How to Install Plugins for Claude Cowork

Unlike Claude Code, which uses CLI commands, Claude Cowork provides a fully web-based installation flow. Follow these steps to add community plugins to your workspace:

1. Visit the plugin store – Navigate to https://claude.com/plugins/ in your browser.

2. Browse or search – The interface displays every entry from the repository's /.claude-plugin/marketplace.json file. Use the search functionality or browse categories to find specific tools.

3. Click "Install" – Selecting a plugin registers it to your Claude Cowork account. The platform records your selection in the backend.

4. Refresh Claude Cowork – Newly installed plugins become available the next time you start a chat session. Existing conversations will not retroactively gain access to newly added plugins.

Key Repository Files

Understanding the repository structure helps clarify how the installation process works under the hood:

• .claude-plugin/marketplace.json – The static manifest that the Claude Cowork web UI reads to display all available community plugins. This file is maintained as a read-only mirror and updates nightly.

• README.md (section "Using this marketplace") – Documents the public installation path specifically for Claude Cowork users, distinguishing it from the CLI-based Claude Code workflow.

• tres-finance-plugin/.claude-plugin/plugin.json – An example plugin definition file demonstrating the JSON schema that defines a plugin's capabilities, permissions, and entry points.

• testdino/.claude-plugin/plugin.json – Another representative sample showing the standardized structure for plugin metadata.

Programmatic Marketplace Access

While installation requires the web UI, you can inspect the marketplace contents programmatically for reference or automation purposes:

import json
import urllib.request

url = "https://raw.githubusercontent.com/anthropics/claude-plugins-community/main/.claude-plugin/marketplace.json"

with urllib.request.urlopen(url) as resp:
    marketplace = json.load(resp)

print(f"Available plugins: {len(marketplace['plugins'])}")
for plugin in marketplace['plugins']:
    print(f"- {plugin.get('name', 'Unnamed')}")

Note: This script retrieves the public manifest for inspection only. According to the repository's source code, actual installation and activation must occur through the authenticated Claude Cowork web interface at claude.com/plugins.

Claude Cowork vs. Claude Code: Critical Distinction

The anthropics/claude-plugins-community repository contains CLI command examples in its README, but these instructions target Claude Code, Anthropic's terminal-based coding assistant. For Claude Cowork, the browser-based collaboration platform, the installation process is entirely web-driven as documented in the README section "Using this marketplace" (lines 13-22). Attempting to use CLI commands in the Cowork environment will not register plugins, as the Cowork platform strictly validates installations through its web UI to maintain security and permission integrity.

Summary

• Web-only installation: Claude Cowork requires visiting claude.com/plugins to install plugins; CLI methods are reserved for Claude Code.
• Manifest-driven: The platform reads from .claude-plugin/marketplace.json to populate the store catalog.
• Restart required: Plugins activate on the next chat session after installation, not immediately in active conversations.
• Read-only registry: Direct pull requests to the community repository are automatically closed; submissions must go through the official portal at clau.de/plugin-directory-submission.

Frequently Asked Questions

How do I install plugins for Claude Cowork?

To install plugins for Claude Cowork, open https://claude.com/plugins/ in your browser, browse the available community plugins sourced from the anthropics/claude-plugins-community repository, and click the "Install" button on your chosen extension. The plugin will be available the next time you start a new chat in Claude Cowork.

Can I submit a new plugin via GitHub pull request?

No. Because the repository maintains a read-only mirror of the marketplace, direct pull requests are automatically closed. You must submit new plugins through the official submission portal at clau.de/plugin-directory-submission, where Anthropic reviews and approves entries before adding them to the nightly-generated manifest.

What is the difference between marketplace.json and plugin.json?

The .claude-plugin/marketplace.json file serves as the central catalog that lists all approved plugins with basic metadata, while individual plugin.json files (located within each plugin's subdirectory like tres-finance-plugin/.claude-plugin/) contain the detailed configuration, skill definitions, and permission requirements for specific extensions.

Why doesn't my installed plugin appear in my current conversation?

Claude Cowork loads the plugin environment when a chat session initializes. If you install a plugin while a conversation is active, you must start a new chat session for the platform to load the newly registered plugin bundle and make its tools available to Claude.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}