Unreal Engine MCP

Italiano

An MCP server that lets an AI agent drive Unreal Engine 5: create projects, import assets, build levels and Blueprints, configure replication, compile C++, run Play In Editor and package the game.

No C++ plugin to compile. It uses two plugins that already ship with the engine — Python Editor Script Plugin and Remote Control API — and talks to the editor over local HTTP.

                    ┌─ LOCAL layer  ── processes + public HTTP
                    │    UnrealEditor.exe, UnrealBuildTool, RunUAT, asset downloads
Agent ──stdio──▶ MCP │
                    └─ EDITOR layer ── HTTP :30010 (Remote Control API)
                         └─ ExecutePythonCommandEx → running editor

The local layer exists because the Remote Control API only works against an editor that is already running: creating a project, launching it, compiling and packaging all have to happen at the process level.

• 49 tools — full reference
• 91 tests, none of which need Unreal installed
• Unreal automation notes — the API traps found the hard way

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Requirements

• Unreal Engine 5.0 or newer (developed and tested against 5.8 — see version compatibility)
• Python 3.10+
• Windows for the local layer (process handling and build scripts are Windows-specific). The editor layer is platform-neutral.

Unreal version compatibility

The server detects what the running engine supports at startup of each call — ue_status reports it under capabilities — and fails with an explicit message instead of a cryptic Python error when a feature is missing:

Feature	Works on
Actors, levels, spawn/transform, PIE, project settings, build & packaging, Sound Cues	5.0+
Blueprint creation, components (SubobjectDataSubsystem)	5.0+
glTF/.glb import via Interchange	5.2+ (earlier: enable the glTF Importer plugin; the tool tells you when that is the problem)
Blueprint member variables + per-variable replication (ue_add_variable)	5.4+ (no Python API before that — the tool says so explicitly)
MetaSounds	any 5.x with the MetaSound plugin enabled

Custom engine builds are fine: detection is based on the actual Python API surface, not on the version number.

Install

git clone https://github.com/FFZackFair92/unreal-engine-mcp.git
cd unreal-engine-mcp
pip install -e .

Connect it to your client

The server speaks standard MCP over stdio, so any MCP-capable client works — Claude, Cursor, VS Code, Windsurf, OpenAI Codex, custom agents. The command is always the same; only where the config lives differs.

Claude Desktop / Cowork

Settings ▸ Developer ▸ Edit Config, then add to mcpServers:

{
  "mcpServers": {
    "unreal-mcp": {
      "command": "python",
      "args": ["-m", "unreal_mcp.server"],
      "env": { "UE_MCP_PORT": "30010" }
    }
  }
}

Claude Code

claude mcp add unreal-mcp -- python -m unreal_mcp.server

Cursor

~/.cursor/mcp.json (global) or .cursor/mcp.json in the project — same JSON shape as Claude Desktop (mcpServers root key).

VS Code (Copilot agent mode)

.vscode/mcp.json — note the root key is servers here:

{
  "servers": {
    "unreal-mcp": { "type": "stdio", "command": "python", "args": ["-m", "unreal_mcp.server"] }
  }
}

Windsurf

~/.codeium/windsurf/mcp_config.json — same mcpServers shape as Claude Desktop.

OpenAI Codex CLI

~/.codex/config.toml:

[mcp_servers.unreal-mcp]
command = "python"
args = ["-m", "unreal_mcp.server"]

OpenAI Agents SDK (custom agents)

from agents.mcp import MCPServerStdio

unreal = MCPServerStdio(params={"command": "python", "args": ["-m", "unreal_mcp.server"]})

Restart the client completely after editing its config. In every case python must be the interpreter where you ran pip install -e . — use an absolute path if in doubt.

Note: ChatGPT's connector UI only accepts remote MCP servers. This server is stdio/local by design (it drives processes on your machine), so use it from clients with stdio support — the ones above — or wrap it with an MCP proxy if you really need HTTP.

Set up the Unreal side

Starter project — zero setup, zero builds

Copy StarterProject/ wherever you like and open the .uproject with any UE 5.0+: plugins enabled, security config in place, web server auto-started. Being Blueprint-only with engine plugins, there is nothing to compile — unlike starters that bundle a C++ plugin.

New project — nothing to do by hand

Ask the agent to run ue_project_create. It writes the .uproject with the required plugins enabled, the security flags Remote Control needs, and an init_unreal.py that starts the web server on every editor launch.

ue_engine_list  →  ue_project_create  →  ue_editor_open  →  ue_status

Existing project — three steps

1. Enable the plugins: Edit ▸ Plugins → Python Editor Script Plugin and Remote Control API. Restart when prompted.

2. Allow remote Python. Create Config/DefaultRemoteControl.ini:

   [/Script/RemoteControlCommon.RemoteControlSettings]
   bAutoStartWebServer=True
   bAutoStartWebSocketServer=True
   RemoteControlHttpServerPort=30010
   bEnableRemotePythonExecution=True
   bAllowConsoleCommandRemoteExecution=True
   bAllowAnyRemoteFunctionCall=False
   +CustomAllowedRemoteFunctionCalls=(ClassPath="/Script/PythonScriptPlugin.PythonScriptLibrary")
   

   These are two separate gates — one unlocks the object, the other the function call — and they fail with different errors. DefaultEngine.ini is the wrong file: URemoteControlSettings is declared UCLASS(config = RemoteControl). Restart the editor.

   On engines that predate some of these keys they are simply ignored — older versions did not gate those calls in the first place.

   The server listens on 127.0.0.1 only, so remote Python execution is not reachable from outside the machine.

3. Check it: open http://127.0.0.1:30010/remote/info in a browser. JSON back means you are connected.

What it can do

Area	Highlights
Projects	Find engine installs, create projects from a spec, manage plugins
Editor lifecycle	Open (waiting for the bridge), status, clean shutdown
Build	Compile C++ in the background; ue_live_compile recompiles with the editor open via Live Coding
Package	RunUAT BuildCookRun → standalone executable, with phase reporting
Assets	Import .glb/.gltf/.fbx/.wav, list and search the Content Browser
Levels	Create and open levels, spawn/move/delete actors
Blueprints	Create, add components, typed variables with replication, class defaults, compile
Networking	Replication flags, multi-client PIE, project settings
Audio	Import wavs, MetaSound sources, Sound Cues
Free assets	Poly Haven, ambientCG and Kenney downloads (all CC0), plus any direct URL

Full parameter list in docs/TOOLS.md.

Known limits

• Blueprint node graphs cannot be authored. UE 5.8 does not expose graph editing to Python: EdGraph.Nodes is protected, pins are not exposed and there is no linking API. Variables, components and defaults are scriptable; logic belongs in C++ or in the editor. Details in docs/UNREAL-NOTES.md.
• Compiling C++ needs the editor closed, unless the change only touches function bodies — then ue_live_compile works with it open.
• Packaging always needs the editor closed: the build step rewrites the DLLs the editor holds in memory.
• Feature availability varies with the engine version — see the compatibility table; ue_status reports what the running engine supports.
• Fab/Marketplace content has no public API. Those tools shell out to the community client legendary.

Configuration

Variable	Default	Purpose
UE_MCP_HOST / UE_MCP_PORT	127.0.0.1 / 30010	Remote Control endpoint
UE_MCP_TIMEOUT	180	Per-call timeout in seconds
UE_MCP_ENGINE_DIRS	—	Extra folders to search for engine installs
UE_MCP_LIBRARY	~/UnrealAssetLibrary	Where downloaded assets land
UE_MCP_MAX_DOWNLOAD	4 GiB	Per-file download cap

If the engine sits somewhere unusual, you can also drop an mcp_engine.txt next to the .uproject containing its path, or pass engine_root explicitly.

Development

The test suite runs without Unreal installed: tests/fake_unreal.py stands in for the unreal module and tests/fake_server.py emulates the Remote Control API while actually executing the generated snippets — so the whole chain tool → snippet → harness → result is covered.

pip install -e ".[dev]"
pytest -q

Adding a tool: a reusable helper in src/unreal_mcp/ue_side.py (editor side), an @mcp.tool() function in server.py, and a test in tests/. ue_side.py is re-read from disk on every call, so editor-side changes take effect without restarting the server; changes to server.py or local.py need a client restart.

Troubleshooting

Symptom	Cause
No response from http://127.0.0.1:30010	Editor closed, or the web server never started → console: WebControl.StartServer
Object Default__PythonScriptLibrary cannot be accessed remotely	Missing bEnableRemotePythonExecution in DefaultRemoteControl.ini
Executing function 'ExecutePythonCommandEx' is not allowed	Missing CustomAllowedRemoteFunctionCalls entry
404 on /remote/object/call	Remote Control API plugin not enabled
NameError: name 'unreal' is not defined	Python Editor Script Plugin not enabled
Unable to build while Live Coding is active	LiveCodingConsole.exe outlives the editor — kill it (the build tools do this automatically)
No Unreal Engine installation found	Set UE_MCP_ENGINE_DIRS, add mcp_engine.txt, or pass engine_root

Licence

MIT — see LICENSE.

References

• Remote Control for Unreal Engine
• Remote Control Quick Start
• Importing glTF files
• Poly Haven API · ambientCG API