How to Build in Minecraft With AI: Claude Code Places the Blocks

Type "Build a castle" into Minecraft and watch it go up block by block while you keep playing. The maker of a free mod called Voxelwright AI reports exactly that: a 34,738-block castle with towers, walls and a gate, from that one request, in 15 minutes.

The mod has no AI of its own. It hands your request to Claude Code, Anthropic's coding agent, running on your computer and signed in with your own Claude plan. Claude plans the build, then places the blocks through the game's own commands. You can type the request after pressing K, or hold V and say it.

If you heard of it as CRAFT AI, it is the same mod. Its maker renamed it Voxelwright AI in beta 0.14.0 on October 16, 2026. This guide walks through the whole setup, how to write requests that come out the way you pictured, and what to watch out for.

What Voxelwright AI is and how it builds

Voxelwright AI is a Minecraft mod: one add-on file you drop into the game's mods folder. An independent developer who signs the site "Made by Penra" builds it. Minecraft belongs to Mojang Studios, which Microsoft bought in 2014, and Claude is Anthropic's product. The mod's site says it is not affiliated with or endorsed by Mojang, Microsoft, Anthropic or the Fabric, Forge and NeoForge projects.

Here is what happens after you press K and send a request, according to the maker:

1. The mod starts a small server on your own computer. It listens only on 127.0.0.1, on a random port, with a secret token.
2. It launches your Claude Code and passes it your request, plus what it can read in the game: your position and the blocks around you.
3. Claude plans the build and calls 20 tools that run inside the game. The blocks go down through Minecraft's own /fill and /setblock commands.
4. Every changed block goes into a journal, so Undo (or /undo) restores exactly what was there before, chest contents included.

Your world and requests never pass through a Voxelwright server. The mod contacts its own website only to check for updates and, once, to download the speech model for voice. Your requests do go to Anthropic, because that is where Claude runs.

Before you start

The maker's guide says the whole setup takes about fifteen minutes, once.

Step 1: Install Claude Code

1. Open a terminal: Terminal on a Mac, or PowerShell from the Start menu on Windows.
2. Paste the command for your system and press Enter. You do not need to run it as an administrator.

   Copy# macOS and Linux
   curl -fsSL https://claude.ai/install.sh | bash
   
   # Windows PowerShell
   irm https://claude.ai/install.ps1 | iex

3. When it finishes, open a new terminal window and run claude --version. A version number means it worked.
4. Type claude and follow the sign-in prompt in your browser, with the Claude account that has your subscription. You can also sign in later from inside the game.

On Windows, install Claude Code in Windows itself, not inside WSL, because the game looks for it on the system it runs on. If PowerShell says The token '&&' is not a valid statement separator, you pasted the Command Prompt version of the command. Anthropic's install troubleshooting page covers other errors.

Step 2: Set up Minecraft 26.3 with a mod loader

Pick the loader your other mods already use. If you have none, Fabric is the one with the longest record for this mod. Forge and NeoForge support is new in this version, and the maker has not yet tried voice with a real microphone on either.

With Fabric and the official Minecraft Launcher:

1. Download the installer from the Fabric installer page: the .exe on Windows, the Universal .jar on macOS and Linux (those need Java installed to run it).
2. Close Minecraft and its launcher, then open the installer. On a Mac, if Apple says it cannot verify the file, go to System Settings, then Privacy & Security, and click Open Anyway.
3. Choose Minecraft version 26.3, keep the latest loader version it offers, make sure Create Profile is ticked, and click Install.
4. Open the launcher, choose the new Fabric profile, click Play, then quit. Fabric is installed.

With Forge or NeoForge, run the official launcher at least once first, because their installers need its profile list. Download the installer for 26.3 from the Forge download page or neoforged.net, open it, choose Install client, then start the new profile once and quit. Prism Launcher, the Modrinth App and CurseForge can also create a 26.3 instance with your loader from their own menus, if they offer that loader for 26.3.

Step 3: Download the mod and put it in the mods folder

1. Go to voxelwright.online and click the download button in the Install section. The file is called voxelwright- plus the version number and .jar (0.14.1 when we checked). The same file works with all three loaders. The site lists a SHA-256 hash next to it if you want to check the download.
2. With Fabric only, also download Fabric API from its Modrinth page: the newest file whose name ends in +26.3. Forge and NeoForge need nothing else.
3. Put the file (or files) in the mods folder of the profile you will play with. For the official launcher:

   CopyWindows:  %appdata%\.minecraft\mods
   macOS:    ~/Library/Application Support/minecraft/mods
   Linux:    ~/.minecraft/mods
   Lunar Client (Fabric only):  ~/.lunarclient/profiles/26/mods/fabric-26.3

   On Windows, paste the path into File Explorer's address bar. On a Mac, use Go, then Go to Folder in Finder. In Prism, right-click the instance, choose Edit, open the Mods tab and drag the file in. If there is no mods folder yet, start the game once with that profile.
4. Keep only one copy of the mod. Delete any older voxelwright-*.jar and any craftai-*.jar from before the rename. With two copies you can end up running an older version without knowing it.

Step 4: Start the game and connect Claude

1. Start Minecraft 26.3 with your Fabric, Forge or NeoForge profile, not a plain Minecraft one.
2. Open a single-player world, or a server where you are allowed to use /fill and /setblock.
3. Press K. The Voxelwright AI panel opens over the game, which means the mod loaded. You can change the key in Options, then Controls.
4. Read the welcome screen. It names your Claude account. If it says "Claude: not signed in", click Sign in to Claude, sign in on the browser page that opens, and come back to the game. It notices by itself.
5. You are ready when it says "Claude detected" followed by your plan, for example "Claude detected · Max subscription".

The other messages tell you what to fix. "Claude Code not found" means step 1 did not finish, or your launcher is not passing your PATH on. "Claude: free plan, Pro or Max needed" means the account has no Claude Code. "Claude: API key, not your subscription" means Claude Code is signed in with an API key: run claude in a terminal, type /logout, then /login and pick your Claude account. The mod uses your subscription and ignores any ANTHROPIC_API_KEY variable.

Step 5: Your first build

1. Stand where you want the build, or look at the spot.
2. Press K and type in the field at the top that says "Describe what you want to build…". Start small, for example "a stone mage tower with a pointed roof".
3. Press Enter. A capsule at the top of the screen shows progress. You can close the panel and keep playing while it builds.
4. Watch the blocks appear. A short animation plays when it is done.
5. Not right? Type /undo or use the History tab, then describe what to change. Type /stop to end a build that is going the wrong way.

Requests to try first, from the maker's own gallery:

CopyBuild a castle
Build me a super detailed Nether portal.
Next to the Nether portal, do the same for the End.

Prefer a one-click copy? The same steps are on our free prompt page.

To use your voice, hold V (or click the microphone in the panel), say the request and let go. Speech is turned into text on your computer. The first time, the mod downloads a speech model once: 60 MB for the standard one or 190 MB for the more accurate one, which Macs use by default.

How to write a request that builds what you pictured

The maker's request guide names six parts. You never need all six, and whatever you leave out, Claude chooses for you.

• What: "a lighthouse", "a bridge", "a mage tower".
• Where: look at the spot and say "here" or "over there". With no place, Claude builds in front of you, about 6 to 15 blocks away.
• How big: in words, such as "small", "three floors" or "a whole village".
• Style: the mod knows eight, Medieval, Modern, Futuristic, Japanese, Nordic, Steampunk, Rustic and Fantasy.
• Materials: "dark wood and white plaster", "stone with a slate roof".
• Level of detail: Quick, Detailed or Masterpiece, covered below.

Two of the maker's example requests, one with every part and one with lots of detail:

CopyBuild a stone watchtower over there on the hill, about 20 blocks tall, in Nordic style, with dark wood, a turf roof and torches along the stairs.

Build a lighthouse on a cliff with a tall red and white striped tower, a big lantern at the top, the keeper's house, a staircase cut into the rock and a small jetty.

Three habits save the most time:

• Fence the build in. Type /zone wand, left-click one corner and right-click the opposite one. Claude then builds only inside that zone, and the game refuses any change outside it. Each side can be up to 128 blocks, and the zone stays until you type /zone clear. On a server, look at a block and type /zone 1, then another and /zone 2.
• Change a build instead of repeating the request. Every request draws a random creative direction, so the same sentence twice gives two different builds. Ask "add a garden" in the same conversation and the style stays. After a build, the Create tab offers follow-ups such as Add lighting, Furnish the inside and Night mood.
• Borrow a template. The Templates tab holds 24 ready-written requests in 6 categories, from a country cottage to a stone dragon. Reading a few shows how a full request is put together.

Requests can be in any language, and Claude replies in the language you wrote in. The panel itself comes in English, French, Spanish and German.

Quick, Detailed or Masterpiece

Choose the level in Settings, under Level of detail, or type /detail quick, /detail detailed or /detail masterpiece. The times below are the maker's starting estimates for the mod's default model, Sonnet. The maker calls them typical, not promised.

Start on Quick while you learn how Claude reads your requests, then switch to Masterpiece for the build you want to keep. The time goes into Claude's thinking, not into placing blocks. You can also pick a different Claude model in Settings or with /model.

For a sense of scale, the maker's gallery lists three builds, each in a flat world on an earlier version, with thinking time included: the castle at 34,738 blocks in 15 minutes, a Japanese pagoda at 20,459 blocks in 10 minutes, and a modern villa with a pool at 5,100 blocks in 8 minutes.

What it costs

Every build uses your Claude plan like any other Claude Code session, and Claude counts usage in five-hour sessions. If you plan a long evening of Masterpiece builds, Max's extra usage is what that pays for.

Limits, safety and privacy

• Back up your world first. In single-player the AI acts as your operator and can run any command. Block undo is thorough, but the maker warns that what a command changes cannot always be undone.
• Each build is capped at 100,000 blocks within 384 blocks of you, and nothing changes if a build is refused. The undo journal keeps up to 400,000 blocks per dimension.
• Multiplayer is a beta. Nothing is installed on the server and the AI only has your own permissions. Operators build fast, other players at about one command per second. Undo does not restore chests there, the AI only sees the chunks loaded around you, and it has not been tried on a real dedicated server yet.
• Claude Code sends Anthropic your requests and what the AI reads in the game, such as your position, nearby blocks and player name, under your Claude account's terms.
• The old craftai.world address no longer loads (we checked on October 27, 2026). Download only from voxelwright.online. When an update is out, the mod tells you and installs it with one click, keeping the previous version outside the mods folder.

Troubleshooting

Is a Minecraft AI mod allowed?

For your own copy, yes. Minecraft's end-user license says that if you bought Java Edition you "may play around with it and modify it" with mods. It forbids handing out modded copies of the game itself, and Mojang can take down mods that break its usage guidelines. On someone else's server, the server's rules still apply, so ask the owner before you build on a shared world.

Alternatives, and when to pick them

Voxelwright AI is a builder. If you want an AI that plays alongside you, look at Mindcraft, an open-source project under the MIT license whose team includes MaxRobinsonTheGreat and kolbytn. It runs AI bots that join your world as players, built on the Mineflayer library.

Pick Mindcraft if you are on Java 1.21 (it supports up to 1.21.11 and recommends 1.21.6), or if you want to choose your own model: it works with OpenAI, Anthropic, Google, local models through Ollama and others. The trade-off is setup. It needs Node.js and an API key you pay for per use, and its README warns that it can let a model write and run code on your computer, so that feature is off by default.

Pick Voxelwright AI if you already pay for Claude Pro or Max, you are on 26.3, and you want finished builds.

Who this is not for

Bedrock players and anyone on the free Claude plan can stop here. It is also a poor fit for survival purists: the blocks arrive through operator commands, the same ones you would normally need cheats for, so a Claude-built castle is not one you earned the slow way.

Why a business owner should care about a Minecraft mod

Take away the castles and this is a clean picture of an AI agent. Claude gets a short list of tools inside one app (look around, place blocks, undo), a plain-English goal and a fence it cannot cross, then works until the job is done. Swap the game for a CRM, a spreadsheet or an ad account and the setup is the same, pointed at real work. Building that kind of tool-equipped assistant for business software is what our AI automation team does.

Frequently asked questions

Does Voxelwright AI work on Minecraft Bedrock, Xbox, PlayStation or phones?

No. It only runs on Minecraft: Java Edition 26.3 (and fixes such as 26.3.1) with Fabric, Forge or NeoForge, on Windows, macOS or Linux. Bedrock Edition is not supported.

Is Voxelwright AI free?

The mod is free, with no account and no license key. You do need Claude Code on a paid Claude plan. Pro costs $20 a month, or $17 a month billed yearly, and Max starts at $100 a month.

Do I need an Anthropic API key?

No. The mod uses the Claude Code sign-in on your computer and ignores any ANTHROPIC_API_KEY variable. Run claude in a terminal and sign in, or click Sign in to Claude in the mod's panel.

Is CRAFT AI the same mod as Voxelwright AI?

Yes. The maker, Penra, renamed CRAFT AI to Voxelwright AI in beta 0.14.0 on 16 October 2026. The old craftai.world address no longer loads, so download it from voxelwright.online and delete any old craftai jar from your mods folder.

Can the AI break my Minecraft world?

It can change a lot. In single-player it acts as the operator and can run any command, and the maker warns that some command changes cannot be undone. Back up the world, mark a build zone with /zone wand, and use Undo or /undo to restore blocks.

Does it work on multiplayer servers?

Yes, as a beta. Nothing is installed on the server and the AI only has your own permissions. Operators build quickly, other players at about one command per second, and it has not been tested on a real dedicated server yet.

Sources

• Voxelwright AI official site (requirements, limits, privacy, gallery)
• Voxelwright AI install guide and troubleshooting
• Voxelwright AI: how to write a good request
• Claude pricing
• Claude Code quickstart (install commands, sign-in)
• Fabric docs: installing Fabric on Windows
• Minecraft End User License Agreement (mods section)
• Microsoft: Minecraft to join Microsoft (2014)
• GamingOnLinux: Minecraft Java Edition 26.3 Wilderness Bound released
• Mindcraft on GitHub