A terminal entry point connects code agents to Unity

The Unity CLI interface connects Claude or Copilot directly to the runtime. A method to automate testing and avoid compilation times.

Unity is launching a command-line interface, the Unity CLI, to connect code agents, continuous integration pipelines, and in-house tooling to its real-time 3D engine, which is used in everything from video games to industrial simulation and virtual reality. The publisher presents it as a response to feedback from its community, which was demanding greater reliability, access to the runtime, and the ability to keep existing agents in place.

The main benefit comes from the eval command, which executes arbitrary code using Roslyn, the compiler for the C# language used in Unity. It bypasses compilation times and domain reloads—those assembly reloads that freeze the editor for a few seconds after every code modification, a cost that repeats with each iteration.

Furthermore, access extends beyond the editor. In development builds, the CLI controls the runtime—meaning the compiled game while it is running—allowing for live debugging, modifying the state of a game session, or automating test sessions. Custom commands can be written to provide an agent with project-specific context. On the agent side, Unity cites Claude, Codex, Copilot, and local models.

The Unity MCP server remains supported for existing setups, but the publisher now designates the CLI as the recommended path for new projects. A built-in MCP mode allows agents already built on this protocol to keep running. Both tools are becoming free, with no concurrency limits on the MCP server.