Unity CLI Loop by Hatayama is a free Unity integration tool designed to connect AI agents directly to the Unity Editor. This platform-specific solution enables AI to drive Unity projects, offering assistance for both Editor and Runtime operations. Formerly known as uLoopMCP, it acts as a crucial bridge for automating game development workflows. It supports various AI clients, making it a versatile choice for developers aiming to integrate artificial intelligence into their Unity projects.

What does Unity CLI Loop connect to?

Unity CLI Loop establishes a direct TCP connection with the Unity Editor, acting as a server tool. This connection allows external AI agents to interact with and control Unity projects. It is categorized as a Unity integration tool, specifically built to enable AI to drive Unity Editor and Runtime processes. The tool serves as a direct bridge, enabling AI-powered game development assistance. Compatible AI clients include Claude Code, OpenAI Codex, Gemini, Copilot, Cursor, and other AI clients.

Core features and tools

The Unity CLI Loop exposes several callable tools for AI interaction. These include compile, run-tests, get-logs, and clear-console for project management. For dynamic execution, it offers execute-dynamic-code. Visual and input capabilities include screenshot, simulate-mouse-ui, simulate-mouse-input, simulate-keyboard, record-input, and replay-input. Additionally, the uloop-get-logs skill is available for retrieving console information.

Who is it for?

Unity CLI Loop targets AI agents and developers who are building AI-assisted tooling for Unity. Its purpose is to automate Unity workflows with minimal human intervention, making it suitable for creating autonomous development systems. The tool supports AI-driven operations within the Unity Editor and automated PlayMode testing. This is not the right fit if your goal is manual Unity development without AI integration.

How to get started

The authentication model involves opening the Unity CLI Loop settings within the Unity Editor and pressing the "MCP button." Following this, users select and configure their target LLM tool, such as Claude Code, to automatically connect to the integrated development environment. The broader Unity MCP framework, which this tool relates to, typically requires approving external client connections within Unity's Project Settings under "AI > Unity MCP Server." Communication with Unity occurs directly via TCP connection.

Use cases

• A self-hosted development loop where AI autonomously compiles, tests, inspects logs, and fixes issues.
• AI-driven Unity Editor operations such as scene building, object manipulation, menu execution, and UI refinement from screenshots.
• Automated PlayMode testing, where AI can simulate mouse and keyboard input, record and replay input, and verify game behavior.

Unity CLI Loop offers a powerful bridge for AI agents to interact with the Unity Editor, enabling advanced automation of game development. It supports a range of AI clients and provides tools for compilation, testing, input simulation, and dynamic code execution. The tool is ideal for developers creating AI-assisted workflows, aiming to reduce manual intervention in Unity projects. Start by configuring an AI client like Claude Code to connect to the Unity Editor for automated compilation and testing.