agentmods.dev

setup-server

A setup procedure for configuring and running the Minecraft Java MCP server embedded in a Fabric mod. MCP is a way for software tools to communicate with an agent through defined commands.

In plain words
What is it for?
Use it to set the server host, port, authentication, and tool categories, launch Minecraft or a dedicated server, verify the server is listening, and obtain its bearer token when needed.
Why use it?
It handles the configuration details needed for single-player or dedicated Minecraft servers, including network settings, authentication, health checks, and remote access tokens.

Skill for Claude CodeCodex

6 5d ago B scan 82 tokens original MIT
View the source file chapmanjw/minecraft-java-fabric-claude-plugin
Install

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.

agentmods
npx agentmods add skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-server
Any agent
npx skills add chapmanjw/minecraft-java-fabric-claude-plugin --skill setup-server
Clone the repo
git clone --depth 1 https://github.com/chapmanjw/minecraft-java-fabric-claude-plugin

Made for: Claude Code, Codex.

Per session 82 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,599 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00082 $0.02599
Opus 5 $0.00041 $0.01300
Sonnet 5 $0.00016 $0.00520
Haiku 4.5 $0.00008 $0.00260

Measured 2d ago against content hash 8b701d951443, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

setup-server scanned grade B with 2 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 2d 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.

Unrestricted tool accessmediumExcessive agency

A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.

it can technically run any command, including admin-equivalent ones. Treat the

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl http://localhost:8765/healthz
skills/setup-server/SKILL.md · 255 lines

How it starts

The opening of the file, as written. The whole thing — 255 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Configure and run the MCP server (Step 3 of 4)

This is Phase 3 of the four-phase Minecraft Java MCP setup. It assumes Phase 2 (setup-mod) is done: the MCP mod jar and Fabric API jar are in mods/. The MCP server is embedded in the mod, so "running the MCP server" means launching Minecraft (single-player) or the dedicated server.

Work interactively. Branch on the choice from Phase 1: single-player is mostly defaults; dedicated/remote needs a config file and a token.

Where config lives

The mod reads config/minecraft_fabric_mcp/config.json under the game directory:

  • Single-player: <.minecraft>/config/minecraft_fabric_mcp/config.json.
  • Dedicated server: <server>/config/minecraft_fabric_mcp/config.json.

The file is optional — it's only needed to override defaults. Any field can also be overridden by an environment variable named MCP_<FIELD> (e.g. MCP_PORT, MCP_AUTH_REQUIRED).

The defaults are deliberately safe: bind 127.0.0.1, port 8765, no auth, reject all cross-origin browser requests.

There are two servers. The above is the world server (minecraft-java, the main entrypoint). The same jar also has a client inspection server (minecraft-java-client, the client entrypoint) that runs inside a real, rendered Minecraft client and serves the client category — view_capture (a real first-person PNG) and sense_* / client_status. It reads a separate config config/minecraft_fabric_mcp/client.json (default port 8766, env prefix MCP_CLIENT_*) and defaults to exposing only the inspection tools. It needs a real client window with a GPU — it is not part of a headless dedicated server. This phase configures the world server; running the inspection server (and the server-only / client-only / combo patterns) is covered in setup-connect. Most fields below apply to both — only the file name, default port, and env prefix differ.

Single-player branch — defaults are enough

Read the full file on GitHub · 255 lines

Changes

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.

  1. 2d ago First seen · 255 lines · 82 tokens per session scan B 8b701d951443

Subscribe to this mod's changes

setup-server is a skill published in the GitHub repository chapmanjw/minecraft-java-fabric-claude-plugin (6 stars, last pushed 5d ago), licensed MIT. It adds 82 tokens to every session and 2,599 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it B with 2 findings (unrestricted tool access, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Game developmentclaudemcpmcp-serverminecraftminecraft-javaminecraft-mod
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