Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-fabricnpx skills add chapmanjw/minecraft-java-fabric-claude-plugin --skill setup-fabricgit clone --depth 1 https://github.com/chapmanjw/minecraft-java-fabric-claude-pluginWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-fabric)<a href="https://agentmods.dev/skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-fabric"><img src="https://agentmods.dev/badge/skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-fabric.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00080 | $0.01507 |
| Opus 5 | $0.00040 | $0.00754 |
| Sonnet 5 | $0.00016 | $0.00301 |
| Haiku 4.5 | $0.00008 | $0.00151 |
Grade A, and why
setup-fabric scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 147 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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 supports 1.21.11, 26.1.1, 26.1.2, and 26.2. Default to the newest the user is comfortable with (26.2). Record the exact version — it must match the mod jar and Fabric API jar in Phase 2. The mod jar declares an EXACT Minecraft dependency, so a mismatch is refused at load with a clear message rather than failing later.
- (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.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 5d ago First seen · 147 lines · 80 tokens per session scan A 90c334557e62
setup-fabric is a skill published in the GitHub repository chapmanjw/minecraft-java-fabric-claude-plugin (6 stars, last pushed 8d ago), licensed MIT. It adds 80 tokens to every session and 1,507 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
Other skills, from other repositories
minecraft-dev
Use this skill whenever the user wants to look up Minecraft source, mod source, mod loader source, mappings, registries, versions, version differences, access transformers, mixin information, documentation, or code search results with minecraft-dev-cli. Also use it for Fabric, Forge, Quilt, and NeoForge source lookups.
ashfox
Create, edit, review, animate, and export game-ready low-poly assets in the ashfox web workbench through an AI agent. Use for low-poly modeling, deterministic textures and UVs, rigs, idle or motion animation, GLB, Bedrock, or GeckoLib exports, and Blockbench-free asset production.
1201-forge-modding
Minecraft 1.20.1 Forge Moddingに関する開発支援。Modの新規作成、Block/Item/Entityの追加、 DataGen、ネットワーク処理、レシピ・進捗・ルートテーブルの生成、Capabilityの実装、 クラッシュ対応など。Minecraft 1.20.1 Moddingに関するタスクや、Gradle/MDKのセットアップ、 Registry/Event/sidednessに関する質問があった際に使用する。.
1211-neoforge-modding
Minecraft 1.21.1 NeoForge Moddingに関する開発支援。Modの新規作成、Block/Item/Entityの追加、 DataGen、ネットワーク処理（Payload System）、レシピ・進捗・ルートテーブルの生成、 Capability/Data Component/Data Attachmentの実装、クラッシュ対応など。 Minecraft 1.21.1 NeoForge Moddingに関するタスクや、ModDevGradleのセットアップ、 Registry/Event/sidednessに関する質問があった際に使用する。.
1201-mods-exsample
Minecraft 1.20.1 Forge Moddingにおける実践的な実装パターン集。 エネルギー・GUI・ネットワーク・マルチブロック・レシピ・レンダリング・ スペル/AI/スクリプトなどの設計パターンを、17の主要Modの実装から抽出して解説。 Addon作成に使える部分は各Modトピックとして維持しつつ、Modに依存しない アーキテクチャ知識として整理する。.
1211-mods-exsample
Minecraft 1.21.1 NeoForge Moddingにおける実践的な実装パターン集。 エネルギー・GUI・ネットワーク・マルチブロック・レシピ・レンダリング・ スペル/AI/スクリプトなどの設計パターンを、16の主要Modの実装から抽出して解説。 Forge 1.20.1 → NeoForge 1.21.1 の移行差分（Data Component・Payload System・ Data Attachment）を加味したNeoForge版パターン集。.