| name | setup-fabric |
| description | Step 1 of 4 of the Minecraft Java MCP setup. Install Minecraft Java Edition with the Fabric loader — either a single-player client or a headless dedicated server — as the foundation the MCP mod runs inside. Use when the user wants to set up Minecraft Java for AI/MCP control from scratch, or asks how to get Fabric running so Claude can build in their world. |
Install Minecraft Java + Fabric (Step 1 of 4)
You are guiding the user through the first of four setup phases. Work
interactively: do one thing, confirm it worked, then move on. Do not dump the
whole procedure at once.
The big picture — explain this first
The user is building a stack that lets Claude read and change a live Minecraft
Java Edition world. Unlike a separate server process, the MCP server is a
Fabric mod that runs inside Minecraft itself. There are four setup phases,
one per skill, run in order:
| Phase | Skill | What it does |
|---|
| 1 | setup-fabric (this one) | Minecraft Java Edition with the Fabric loader. |
| 2 | setup-mod | The MCP mod jar + its matching Fabric API jar in mods/. |
| 3 | setup-server | The mod's config.json, launched and verified on /healthz. |
| 4 | setup-connect | Register the MCP server with Claude so the Java tools appear. |
Tell the user this is Phase 1, and that each phase ends by handing off to the
next. Budget ~10 minutes for a single-player setup, ~20–30 for a dedicated
server.
Pin your versions — say this out loud. The mod ships a separate jar per
Minecraft version, built against that version's Fabric API. A Minecraft or
Fabric update can break the modding surface the mod depends on. Pick a
supported Minecraft version, pin it, disable auto-update for that profile,
and upgrade Minecraft, the Fabric API jar, and the mod jar together.
Gather context
Ask the user, before downloading anything:
- Single-player or dedicated server?
- Single-player (recommended default): Claude edits the world you play
in, on your own machine. Loopback only, no token, no firewall changes.
~10 minutes.
- Dedicated server: a headless Minecraft server (for friends, or to keep
the MCP endpoint up 24/7). LAN/remote access with a bearer token.
Branch the rest of this skill on their answer.
- Which Minecraft version? The mod's v0.1.0 supports 1.21.11,
26.1.1, and 26.1.2. Default to the newest the user is comfortable
with (26.1.2). Record the exact version — it must match the mod jar and
Fabric API jar in Phase 2.
- (Dedicated server only) What OS and where? Linux or Windows; same
machine as Claude, LAN box, or cloud VM. The host needs a JDK: Java 21
for 1.21.11, Java 25 for 26.1.x. (Single-player uses the launcher's
bundled runtime — no separate JDK needed.) The connect step (Phase 4) cares
where it runs, so note their answer.
Single-player branch
Step 1 — Install the Fabric loader
Send the user to the official installer: https://fabricmc.net/use/installer/
- Windows: download and double-click the
.exe.
- macOS / Linux:
java -jar fabric-installer-*.jar.
In the installer, pick the Client tab, select the Minecraft version chosen
above, leave the default install location, and click Install.
Step 2 — Create the profile and the mods folder
Open the Minecraft Launcher. A new Fabric Loader profile should appear.
Launch it once and then exit the game — this first run creates the
.minecraft/mods/ folder Phase 2 drops jars into. The mods folder lives at:
| OS | Path |
|---|
| Windows | %appdata%\.minecraft\mods\ |
| macOS | ~/Library/Application Support/minecraft/mods/ |
| Linux | ~/.minecraft/mods/ |
Confirm with the user that the Fabric profile launched and the mods/ folder
now exists. Record the mods-folder path — Phase 2 needs it.
Dedicated server branch
Step 1 — Install the Fabric dedicated server
Download the Server installer from https://fabricmc.net/use/server/ into a
dedicated directory, then run it (substitute the chosen Minecraft version):
mkdir -p /opt/fabric-mcp
cd /opt/fabric-mcp
java -jar fabric-server-installer-*.jar server -mcversion 26.1.2 -downloadMinecraft
This produces fabric-server-launch.jar and downloads the Minecraft server
jar. On Windows, use a stable path with no spaces (e.g. C:\fabric-mcp); avoid
Program Files and OneDrive-synced folders. Use this folder as <server> for
the rest of setup and record its absolute path.
Step 2 — First run + EULA
Run it once to generate server.properties and eula.txt, then stop it
(Ctrl+C):
java -Xmx2G -jar fabric-server-launch.jar nogui
Open eula.txt and change eula=false to eula=true.
Step 3 — Confirm command access
For Claude's command-backed tools to work, the server must allow operator
commands. In server.properties, confirm sensible defaults (e.g.
gamemode=creative so agents can build freely if that suits the user). The MCP
mod runs tool calls as the console, which has full command permission — no
per-player op is required for the MCP tools themselves.
Wrap up
Confirm with the user (the relevant set for their branch):
Then hand off: tell the user Phase 1 is done and the next step installs the MCP
mod and its Fabric API dependency. Offer to continue with the
setup-mod skill now.
