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How to install Unity’s official Claude Code plugin

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How to install Unity’s official Claude Code plugin

Install Unity’s official Claude Code plugin from the marketplace, pick a scope, and verify that /unity: skills load.

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Unity’s plugin for Claude Code adds a set of Unity skills so you can ask an agent to accomplish tasks in Unity in plain language, instead of front-loading instructions with extra context. Install the plugin, choose the scope that matches how you work, then verify that Claude Code loads the skills. The install is wasted if those skills never show up.

Unity’s AI tools are in beta, so the features and documentation might change. Unity also notes that Claude Code is a third-party product it does not develop, own, or operate. That information may not be up-to-date or complete, and your access and use of Claude Code is governed solely by that product’s terms.

You can install the Unity plugin in two ways: through the Claude Code command line interface, or through the Claude desktop app.

Install in Claude Code

To install within the Claude Code command line interface, add the marketplace, then install the plugin:

/plugin marketplace add Unity-Technologies/unity-agent-plugin

/plugin install unity@unity-agent-plugin

That pair is the whole CLI path inside Claude Code.

Install in the Claude desktop app

  1. Open the Claude desktop app.
  2. Go to the Plugins section.
  3. Select Browse.
  4. Search for Unity. If you cannot find it, add it to the marketplace by URL: select Add > Add marketplace, enter the GitHub marketplace URL below, then select Sync.
  5. Select Install (+).
https://github.com/Unity-Technologies/unity-agent-plugin

If install fails with “marketplace not found,” add the marketplace first, then retry.

Choose a scope

During the installation, Claude Code asks you to choose a scope. Select the one that meets your needs:

  • User scope: available in all your projects. Recommended if you work across several Unity projects.
  • Project scope: shared with everyone who works in this repository. Recommended for a team standardizing on the plugin.
  • Local scope: available to you, in this repository only.

To skip the scope prompt, run the install from your terminal and set the scope there. The command uses user scope by default, so pass a scope option only when you want a different one. For example, to install the plugin for yourself in the current repository only:

claude plugin install unity@unity-agent-plugin --scope local

User scope follows you from project to project. Project scope is shared with everyone who works in this repository, recommended for a team standardizing on the plugin. Local scope keeps the plugin on your machine in the current repository and nowhere else.

Verify the installation

The plugin does nothing useful if Claude Code never loads the skills. Check both of these:

  • Enter /unity: to display the list of Unity plugin skills in the slash menu.
  • Enter /plugin to confirm that unity is installed and enabled.

You want both: skills in the slash menu, and the plugin installed and enabled.

Update the plugin

Claude Code checks for plugin updates after your session starts and updates them in the background. When an update is available, Claude Code prompts you to run /reload-plugins. Otherwise, the new version loads the next time you launch Claude Code.

Auto update is off by default for third-party marketplaces and on by default for official Anthropic marketplaces.

To force a refresh now:

/plugin marketplace update unity-agent-plugin

Use the marketplace update when you want a refresh immediately. Use /reload-plugins when Claude Code already told you an update is waiting.

Troubleshooting

The /plugin command isn't recognized

Your Claude Code version is too old, or /plugin is unavailable in your environment.

  1. Run claude --version.
  2. Update Claude Code. Unity points to Claude Code’s own update documentation for this step, including a manual update path.
  3. Restart your terminal and run claude again.

If /plugin still isn't available, use the plugin browser in the Claude desktop app, or declare the plugin under enabledPlugins in .claude/settings.json. An old CLI that lacks /plugin will not complete the in-session install path; the desktop browser or that settings file is the fallback Unity documents.

The skills don't appear after installing

Clear the plugin cache, then restart and reinstall:

rm -rf ~/.claude/plugins/cache

Do not stop at install success in the UI. Confirm /unity: lists skills after you clear the cache.

Marketplace not found in the desktop app

Add the marketplace first, then retry the install. Follow the desktop steps above, including Add marketplace, the GitHub URL, and Sync.

Limitations

Unity documents two limits. For simple uGUI work, the plugin makes little difference compared to doing it manually. On Sonnet 5, the plugin mainly supplies correctness: Sonnet 5 builds most Unity features without the plugin, but defaults to older approaches.

Next step

Install from the command line or the desktop app, pick user, project, or local scope, then confirm /unity: lists skills and /plugin shows unity installed and enabled. If skills never appear, clear the plugin cache and reinstall. For a description of the skills and how to prompt them, use Unity’s “About Unity's plugin” page in the same docs set.

Sources