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Add Unity-MCP (AI Game Developer) to Claude Code

Click Configure for Claude Code in Unity's AI Game Developer window, then start Claude Code from the project folder and approve the server.

Unity-MCP lets Claude Code build scenes and read the console inside your open Unity project. Click Configure for Claude Code in Unity's AI Game Developer window, then start Claude Code from the project folder.

Keep Unity open, because the plugin starts the server when the Editor opens. Claude Code asks you to approve the new server the first time, and the Cloud endpoint also needs a sign-in through /mcp.

Good for

  • Unity developers who already work in Claude Code
  • Solo devs who want Claude to build scenes and fix console errors
  • Teams that want to share one project setup through .mcp.json
  • Anyone trying to keep tool descriptions out of Claude's context

Add Unity-MCP (AI Game Developer) to Claude Code

Claude Code

  1. 1

    Open your Unity project (the plugin must already be installed, and the project path cannot contain spaces).

  2. 2

    Open Window/AI Game Developer.

  3. 3

    Click Auto-generate Skills (recommended) or Configure MCP for Claude Code.

  4. 4

    Keep Unity open, then start claude from the Unity project root, where Configure wrote .mcp.json.

  5. 5

    Approve the ai-game-developer server when Claude Code asks, then run /mcp to sign in if it asks you to.

Requires Unity project (path without spaces), Unity-MCP plugin installed, ai-game.dev account (Cloud mode).

Read-only mode: There is no read-only switch. Leave the Unity tools on Claude Code's ask prompt and add no allow rule for the whole server. Claude Code's permission rules use the pattern mcp__<server>__*, so that would be mcp__ai-game-developer__* here, or mcp__ai-game-dev__* for the Cloud command.

Pick the Unity window first. It writes .mcp.json in your project root and, with Auto-generate Skills, skill files in .claude/skills. Open Unity before you start Claude Code. If Claude Code lists no Unity tools, restart it once Unity shows it is connected.

Claude Code asks you to approve a server from .mcp.json the first time. For the Cloud endpoint, run /mcp and finish the browser sign-in. The local port is chosen per project (20000 to 29999), so do not expect 8080.

If you paste a .mcp.json from the ai-game.dev page, add the "type": "http" line. Do not commit a .mcp.json that contains an Authorization header or project key.

From the project README. Source.

Common errors and fixes

  • Claude Code lists no Unity tools after you add the server

    Cause: Claude Code started before Unity was open and connected, so there was no server to reach.

    Fix: Open the project in Unity, wait until it shows connected, then restart Claude Code. Start `claude` from the project root.

    claude-code Source

  • The ai-game.dev server never appears after you paste the sample .mcp.json

    Cause: The sample has a url but no type, and Claude Code skips an entry without one.

    Fix: Add `"type": "http"` to the entry, or run `claude mcp add --transport http ai-game-dev "https://ai-game.dev/mcp"` instead.

    claude-code Source

  • Every request returns unauthorized after a Claude Code update

    Cause: The saved sign-in no longer matches what Claude Code sends.

    Fix: Sign in again in Unity's AI Game Developer window, press Configure for Claude Code, then restart Claude Code.

    claude-code Source

  • Connection to the local server times out over HTTP on Windows

    Cause: The HTTP connection to the local server did not complete on one setup, while stdio worked.

    Fix: Switch the transport to stdio in the AI Game Developer window, or update Claude Code and try HTTP again.

    claude-code Source

  • HTTP connection drops seconds after starting and Claude Code does not recover

    Cause: An older plugin dropped the HTTP connection, and Claude Code does not reconnect by itself.

    Fix: Update the plugin in Unity, then restart Claude Code. This was fixed in later plugin versions.

    claude-code Source

  • Claude Code cannot connect to the local server after Configure

    Cause: A generated config once pointed Claude Code at a path the local server rejected.

    Fix: Update the plugin, sign in and press Configure again, then run `/mcp` in Claude Code to sign in.

    claude-code Source

  • The server does not start, or the stdio command finds no program

    Cause: The project path may contain spaces, or Unity has not yet downloaded the server into the Library folder.

    Fix: Move the project to a path without spaces and open it in Unity once. Then run the stdio command again.

    claude-code Source

Permissions

High risk

Claude can run C# and change or delete project files in your open Unity project, and there is no read-only mode. Keep Unity tools on Claude Code's per-call prompt, commit your project first, and keep any project key out of git.

What it can do

  • Read your data
  • Create and change things
  • Delete things
  • Read-only mode

Watch out for

  • Claude can run any C# code in your Editor

    Unity-MCP can compile and run C# and call any method. Leave these on Claude Code's per-call prompt instead of allowing every Unity tool at once. github.com

  • Keep a project key out of the shared .mcp.json

    A Cloud config written after a CLI sign-in can carry a non-expiring project key. Do not commit it, or write the config with --oauth so it holds only the address. github.com

  • Claude Code asks before using the project server

    The first interactive start asks you to approve the server from .mcp.json. Read the entry before you approve it, especially in a project you did not create. code.claude.com

  • Skills run through Bash prompts

    Each generated skill calls unity-mcp-cli, so Claude Code asks about a shell command, not an MCP tool call. Check the command before you approve it. github.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details
Turning on read-onlyNo read-only mode. Hide tools in the AI Game Developer window or with unity-mcp-cli configure --disable-tools, but a hidden tool still runs if called by name. In Claude Code, keep Unity tools on ask and add no server-wide allow rule (the documented pattern is mcp__<server>__*, here mcp__ai-game-developer__*).
Talks toai-game.dev (Cloud mode only). Download of the server program on first load
Sign-in and keysCloud mode keeps your ai-game.dev sign-in on your machine. A CLI sign-in can also write a project key into .mcp.json.

Works in

Claude Code is documented and listed first, with one open display issue in Unity's connection list.

Tap an app to see how to set it up and any known problems.

Questions

Why does Unity-MCP not show up in Claude Code?

Open Unity first, wait until it shows as connected, then restart Claude Code. Start claude from the Unity project root so it finds .mcp.json, and approve the server when it asks. Run /mcp to check the status.

Where is the Claude Code config file?

In a .mcp.json at your Unity project root, under the name ai-game-developer. Auto-generate Skills also writes skill files to .claude/skills. Configure picks the local port for you.

Why does Claude Code say the server has a url but no type?

The sample .mcp.json on ai-game.dev has only a url, and Claude Code skips an entry without a type. Add "type": "http" to it, or use the claude mcp add --transport http command from the install box.

How do I sign in from Claude Code?

Start Claude Code, run /mcp and follow the browser prompt. If calls come back unauthorized, sign in again in Unity's AI Game Developer window, press Configure for Claude Code again, then restart Claude Code.

Can I use an access token instead of browser sign-in?

Yes. The Cloud endpoint accepts a personal access token sent as a header, and the install box shows the command for it.

Should I use Skills or MCP in Claude Code?

The project recommends Skills. Claude reads a skill only when it needs it, so fewer tokens go to tool descriptions. If you switch, remove the MCP entry so the tools are not loaded twice.

Does Unity-MCP use up Claude Code's context?

One user reported about 36k tokens for the Unity tools in November 2025, before tool toggles existed. Claude Code now loads tool definitions only when needed, and you can hide unused tools in Unity's window.

Should I connect over HTTP or stdio?

Both work. If HTTP times out, as it did on one Windows PC, switch to stdio in the AI Game Developer window.

How do I make it read-only in Claude Code?

You can't. Keep the Unity tools on Claude Code's ask prompt and do not add an allow rule for them. Hiding a tool in Unity does not block it if it is called by name.

Can I use Claude Code in WSL with a Windows Unity project?

Yes. In 2025 users shared a setup that adds the Windows server program with claude mcp add-json, using a /mnt path to the .exe, at local scope. The maintainer says WSL is not needed, because Configure works for Claude Code on Windows.

Information

updated Nov 1, 2026

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More on this

Sources

Docs, issue trackers and discussions this page is built from.

Show all 23
  1. Unity-MCP README · github.com
  2. Unity-MCP README: automatic configuration · github.com
  3. unity-mcp-cli README: setup-mcp · github.com
  4. unity-mcp-cli README: setup-skills · github.com
  5. Unity-MCP endpoint info · ai-game.dev
  6. Connect Claude Code to tools via MCP · code.claude.com
  7. Unity-MCP README: command line configuration · github.com
  8. Unity-MCP CLI agent registry · unpkg.com
  9. Getting Started (wiki) · github.com
  10. Getting Started (wiki) · github.com
  11. Unity-MCP README: install plugin · github.com
  12. Unauthorized after Claude Code update · github.com
  13. streamableHttp: 202 response to notifications/initialized never completes · github.com
  14. HTTP disconnects seconds after connecting agent terminal or IDE · github.com
  15. new generated configuration breaks custom connections from claude and codex · github.com
  16. Troubleshooting (wiki) · github.com
  17. Unity-MCP README: skills and tools reference · github.com
  18. Limit Token Usage · github.com
  19. Unity-MCP README: variables · github.com
  20. 36K tokens consumed by context window always!!! · github.com
  21. WSL with Windows Unity project · github.com
  22. Unity-MCP README: install AI agent · github.com
  23. Connection list keeps rows for past sessions · github.com

Updated Nov 1, 2026.