Guide: connect Claude and build

What you need

• Minecraft: Java Edition 26.3 with Fabric (Fabric Loader 0.19.5 or later, and Fabric API). CRAFT AI does not work with Forge or NeoForge.
• Java 25, which the launcher usually brings.
• A Claude subscription: Pro, Max, Team or Enterprise. The free plan does not include Claude Code.
• A CRAFT AI licence: 15 €, paid once, for one computer.

1Install Claude Code

CRAFT AI talks to Claude through Claude Code. Install it once, on the computer you play on.

1. Open the Claude Code page and follow the installer for your system. On Windows, use the native installer.
2. Check that it worked: open a terminal and run the command below. A version number means Claude Code is installed.

claude --version

2Install the mod

1. In the Install section, download the CRAFT AI file and Fabric API, and install Fabric Loader for Minecraft 26.3 if you do not have it yet.
2. Put both .jar files in the mods folder of your Fabric profile, and remove any older craftai-*.jar. The usual folder is %appdata%\.minecraft\mods on Windows, ~/Library/Application Support/minecraft/mods on macOS and ~/.minecraft/mods on Linux. With another launcher (Lunar, Prism, Modrinth, CurseForge), use the mods folder of your profile.
3. Start Minecraft 26.3 with Fabric and open a world. Press K to open the CRAFT AI panel (you can change the key in Options → Controls).

3Connect your Claude account

The mod checks your Claude account for you and, if it is not connected, lets you connect it without leaving the game.

From the game (the easy way)

1. Open a world and press K. The welcome screen names your Claude account. If it says Claude: not signed in, click Sign in to Claude.
2. Your browser opens on Claude's sign-in page. Sign in with the account that has your subscription and approve. If the page did not open, click Open the page again.
3. Come back to the game. It notices by itself and writes that you are signed in. If the page shows a code instead of finishing, copy the code and paste it in the message field of the panel, then press Enter: it goes straight to Claude Code, never to the AI.
4. Check: the welcome screen now says Claude detected · Max subscription (or Pro, Team, Enterprise).

From a terminal

1. Open a terminal and run claude.
2. Type /login and choose your Claude account (the one with the subscription).
3. Sign in in the browser, then come back to the game. It looks again as soon as you return to its window.

What the mod checks, and when

• Before every request you send, so the panel is never out of date.
• When you come back to the game window, for example after signing in in the browser or a terminal.
• Every 10 seconds while the panel shows a problem, and every 3 minutes otherwise.
• If your account signs out while you play, the conversation tells you once.

What the panel says, and what to do

4Activate your licence

1. On the Account page, sign in or create an account, then buy your licence (15 €, once). Your licence key appears on your account page.
2. In the game, press K, paste the key in the field at the top (it says “Paste your licence key here…”) and press Enter. The licence is attached to this computer.
3. To check it at any time, type /license. To use CRAFT AI on another computer, type /license release on the first one.

5Your first build

1. Press K. In the field at the top (“Describe what you want to build…”), describe what you want, in any language: “a stone mage tower with a pointed roof”.
2. Press Enter. The capsule at the top of the screen shows the progress. You can close the panel and keep playing.
3. The build appears block by block. A short animation plays when it is done.
4. Not what you wanted? Type /undo, or open the History tab. Describe what to change and try again.

Tips for better builds

• Look at the place where you want it and say “here” or “over there”. The AI sees what you look at and a map of your surroundings.
• Be specific about the style and the materials: “a Japanese pagoda in dark wood and white plaster on the hill”.
• Choose how detailed it should be in Settings, under Level of detail. More detail takes longer.
• To build inside an exact area, select a zone with /zone wand. On a multiplayer server, look at two corners and use /zone 1 and /zone 2.

6Go further

• Voice: hold V, say what you want, let go. Your words become the request. It runs on your computer: your voice never leaves it.
• Undo and redo: /undo, /redo, or the History tab. Type / in the field to see every command.
• Model: choose the Claude model in Settings, or with /model.
• Multiplayer: it works on servers where you are allowed to use /fill and /setblock. Nothing is installed on the server: the mod builds from your computer, with your rights. A player who is not an operator builds at about one command per second.
• Updates: the mod tells you when a new version is out, and one click installs it. Type /update to check.

Troubleshooting