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 skills add chapmanjw/minecraft-java-fabric-claude-plugin --skill setup-servergit 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-server)<a href="https://agentmods.dev/skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-server"><img src="https://agentmods.dev/badge/skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-server/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-server"><img src="https://agentmods.dev/badge/skills/chapmanjw/minecraft-java-fabric-claude-plugin/setup-server.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00082 | $0.02599 |
| Opus 5.5 | $0.00033 | $0.01040 |
| Sonnet 5.5 | $0.00016 | $0.00520 |
| Haiku 4.5 | $0.00008 | $0.00260 |
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 1mo 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 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, themainentrypoint). The same jar also has a client inspection server (minecraft-java-client, thecliententrypoint) that runs inside a real, rendered Minecraft client and serves theclientcategory —view_capture(a real first-person PNG) andsense_*/client_status. It reads a separate configconfig/minecraft_fabric_mcp/client.json(default port 8766, env prefixMCP_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 insetup-connect. Most fields below apply to both — only the file name, default port, and env prefix differ.
Single-player branch — defaults are enough
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.
- 1mo ago First seen · 255 lines · 82 tokens per session scan B 8b701d951443
setup-server is a skill published in the GitHub repository chapmanjw/minecraft-java-fabric-claude-plugin (8 stars, last pushed 1mo ago), licensed MIT. It adds 82 tokens to every session and 2,599 once invoked, about $0.0003 per session on Opus 5.5. 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.
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