game-engine-mcp-tools

Game Engine MCP Tools

Overview

The user can connect live editors to you through MCP servers in Settings → MCP servers. They are optional and disabled by default. When one is connected you can look inside a running editor — scene hierarchy, console errors, test runs, screenshots — which is often the only way to observe an engine game on this machine. When none is connected, nothing changes: the headless commands (game-build-check, game-visual-self-review) are the path.

Core principle: An editor MCP is an extra pair of eyes, never the verdict. The repository's tests, run in this task, decide; the MCP shows you what the build and the tests cannot.

Is it there?

Look at your tool list. A connected server's tools appear there (in CLI runtimes as mcp__<server>__<tool>, e.g. tools under unity, godot, unreal, blender, browser). No tools from it → it is not connected.

• Never ask the user to install, enable or start an editor or MCP server mid-task. Fall back to the headless CLI and say in the closing message what you could not observe.
• A tool call that fails because the editor is closed or busy is a finding, not something to retry in a loop.

First call: is the editor on your workspace?

Editor MCP servers talk to whatever editor the user has open. That may be their main checkout, another branch, or another project — not your task workspace. Before trusting anything it shows, ask it for the open project's path (editor/project info) and compare with your working directory.

• Different path → its scenes, console and tests describe someone else's code. Do not edit through it; use the CLI instead, and note it in the closing message.
• Same path → it sees your files once the editor has refreshed or recompiled them; trigger or wait for that before reading the console or running tests.

What each server is for

Server	What it is	Use it to	Watch out for
unity	MCP for Unity (CoplayDev/unity-mcp); needs its package in the project and the Editor open	Inspect scenes and GameObjects (manage_scene), read console errors and compile errors (read_console), run EditMode/PlayMode tests in the open editor (run_tests), control play mode and editor state (manage_editor), capture editor/game views	An open Editor locks the project, so a batchmode CLI run on the same project fails — run the tests through the MCP instead, and still read their results. UNITY_MCP_DEFAULT_INSTANCE picks the editor when several are open.
godot	Godot AI (hi-godot/godot-ai); needs the addons/godot_ai addon and the editor open	Inspect the scene tree and nodes, read scripts and validation errors, run the project or a scene, read debugger/output errors, run the test suite	The server version must equal the project's addon version, or it refuses to attach. Its server uses port 8000.
unreal	Epic's built-in Unreal MCP (UE 5.8+, "Unreal MCP" plugin, Experimental), loopback HTTP on 127.0.0.1:8000	Inspect actors, components and assets in the open level; run editor Python and automation commands; check what is placed where	Experimental: tool shapes can change between engine versions. Same port 8000 as Godot AI — only one of the two can run. No authentication: anything on this machine can call it.
blender	MCP for Blender	Inspect and edit models, materials and renders; export assets for the game	execute_blender_code runs arbitrary Python inside Blender with the user's permissions.
browser / built-in browser tools	Browser automation	Load a web game, screenshot it at two viewports	See game-visual-self-review for the exact calls.