mcp-unity: Instructions file for Claude Code

CLAUDE.md

mcp-unity CLAUDE.md is an instructions file for Claude Code from pakkio/mcp-unity. It costs 1,242 tokens per session, scanned A, a copy of mcp-unity CLAUDE.md, MIT.

Project instructions for MCP Unity, which connects AI coding tools to the Unity Editor through a Node.js server and WebSocket bridge.

In plain words
What is it for?
Use it when installing dependencies, building or testing the Node.js server, debugging the connection, or working on the Unity side.
Why use it?
It puts the main build, test, and development commands in one place and describes the project’s two parts.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions CLAUDE.md; mentions Claude Code; mentions Codex.

This is pakkio/mcp-unity's own configuration. It tells Claude Code how to work on mcp-unity itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mcp-unity configures →

Reuse

Borrowing it

Nothing to install: this file belongs to pakkio/mcp-unity. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/pakkio/mcp-unity/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/pakkio/mcp-unity

Made for: Claude Code.

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Per session 1,242 This file is loaded in full into every session.
When invoked 1,242 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod 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 5.1 $0.01242 $0.01242
Opus 5.5 $0.00497 $0.00497
Sonnet 5.5 $0.00248 $0.00248
Haiku 4.5 $0.00124 $0.00124

Measured 2mo ago against content hash d9ab468c86df, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

mcp-unity CLAUDE.md 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 2mo 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.

Origin

This is a copy

100% identical to mcp-unity CLAUDE.md — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

CLAUDE.md · 133 lines

How it starts

The opening of the file, as written. The whole thing — 133 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

MCP Unity exposes Unity Editor capabilities to MCP-enabled clients (Cursor, Windsurf, Claude Code, Codex CLI, GitHub Copilot) through a two-tier architecture:

  • Unity Editor (C#): WebSocket server inside Unity that executes tools/resources
  • Node.js Server (TypeScript): MCP stdio server that bridges AI clients to Unity via WebSocket

Data flow: MCP Client ⇄ (stdio) ⇄ Node Server (Server~/src/index.ts) ⇄ (WebSocket) ⇄ Unity Editor (Editor/UnityBridge/McpUnityServer.cs)

Build & Development Commands

Node.js Server (Server~/)

npm install          # Install dependencies
npm run build        # Compile TypeScript to build/
npm run watch        # Watch mode compilation
npm start            # Run server (node build/index.js)
npm test             # Run Jest tests (uses --experimental-vm-modules)
npm run test:watch   # Watch mode testing
npm run inspector    # Launch MCP Inspector for debugging

Unity Side

  • Build/Test via Unity Editor
  • Tools > MCP Unity > Server Window for configuration
  • Window > General > Test Runner for EditMode tests

Key Directories

Editor/                       # Unity Editor package (C#)
├── Tools/                    # MCP tools (inherit McpToolBase)
├── Resources/                # MCP resources (inherit McpResourceBase)
├── Services/                 # TestRunnerService, ConsoleLogsService
├── UnityBridge/              # WebSocket server + message routing
│   ├── McpUnityServer.cs     # Singleton managing server lifecycle
│   └── McpUnitySocketHandler.cs  # WebSocket handler
└── Utils/                    # Logging, config, workspace helpers

Server~/                      # Node.js MCP server (TypeScript/ESM)
├── src/index.ts              # Entry point - registers tools/resources
├── src/tools/                # MCP tool definitions (zod + handler)
├── src/resources/            # MCP resource definitions
└── src/unity/mcpUnity.ts     # WebSocket client connecting to Unity

Read the full file on GitHub · 133 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. 2mo ago First seen · 133 lines · 1,242 tokens per session scan A d9ab468c86df

Subscribe to this mod's changes

mcp-unity CLAUDE.md is an instructions file published in the GitHub repository pakkio/mcp-unity (0 stars, last pushed 2mo ago), licensed MIT. It adds 1,242 tokens to every session, about $0.0050 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to mcp-unity CLAUDE.md, differing in 2 lines, and is treated as a copy.

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