Unreal Engine MCP

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.

176 tools and 5 resources — full reference
435 tests, none of which need Unreal installed
Unreal automation notes — the API traps found the hard way

Requirements

Unreal Engine 5.0 or newer (developed and tested against 5.8 — see
version compatibility)
Python 3.10+
Windows, Linux or macOS. Development happens on Windows, which is where the
local layer is exercised most; the Linux and macOS paths (Build.sh,
RunUAT.sh, pgrep) are implemented and covered by CI, but less battle-tested.
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`), reparenting	5.0+
Materials, material instances, screenshots, C++ class generation	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

pip install unreal-engine-mcp

Or run it without installing anything, if you have uv:

uvx unreal-engine-mcp

Or from source, to hack on it:

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 — two steps

Enable the plugin: Edit ▸ Plugins → Python Editor Script Plugin.
Restart when prompted.
Tick one box: Edit ▸ Project Settings → search Python → check
Enable Remote Execution.

That is the whole setup. The server discovers the editor over the engine's own
Python remote execution channel — no config file, no HTTP port.

The HTTP route (Remote Control API), for when multicast will not do

The native channel finds the editor with a UDP multicast ping on the local
machine. That is the easy path, but it does not cross a subnet, and some
corporate networks and VPN adapters swallow multicast entirely. In those cases
— or with the editor on another machine — use the Remote Control API
instead, with UE_MCP_TRANSPORT=remotecontrol.

Enable the plugins: Python Editor Script Plugin and Remote Control
API. Restart when prompted.
Allow remote Python. Create Config/DefaultRemoteControl.ini:
```
[/Script/RemoteControlCommon.RemoteControlSettings]
bAutoStartWebServer=True
bAutoStartWebSocketServer=True
RemoteControlHttpServerPort=30010
bEnableRemotePythonExecution=True
bAllowAnyRemoteFunctionCall=False
+CustomAllowedRemoteFunctionCalls=(ClassPath="/Script/PythonScriptPlugin.PythonScriptLibrary")
bAllowConsoleCommandRemoteExecution=False
```
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.

What the server can do once connected, and how to open it up safely if you
really need to reach the editor from another machine, is in
SECURITY.md.

bAllowConsoleCommandRemoteExecution stays off. It enables
ExecuteConsoleCommand through the web API, which this server never calls
— the console commands it does need (LiveCoding.Compile,
WebControl.StartServer, HighResShot) are issued from inside Python via
unreal.SystemLibrary.execute_console_command and do not go through that
gate. Older versions of this project set it to True; existing projects can
flip it to False without losing anything.
Check it: open http://127.0.0.1:30010/remote/info in a browser. JSON
back means you are connected.

Which transport is in use

ue_status reports it. By default (UE_MCP_TRANSPORT=auto) the server tries
the native channel first and falls back to HTTP, so a project set up either way
just works. Set pyremote or remotecontrol to pin one.

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
C++	Generate compilable classes with the boilerplate written correctly, then reparent Blueprints onto them
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, batch spawn, set properties on placed actors
Materials	Build material graphs, wire PBR textures, material instances, assign to actors
Blueprints	Create, add components, typed variables with replication, class defaults, reparent, 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
Feedback	`ue_screenshot` captures the viewport, so the agent can see what it built

Full parameter list in docs/TOOLS.md.

Reaching the server from claude.ai on the web

Local clients launch the server over stdio and need nothing else. claude.ai runs
on Anthropic's machines, which cannot reach yours, so it needs an HTTP endpoint
and a tunnel of your own in front of it:

python -m unreal_mcp.server --http

That binds 127.0.0.1:8000; the URL to paste into Settings → Connectors → Add
custom connector is the tunnel's public address with /mcp appended.

A tunnel publishes a server exposing ue_exec_python to the internet —
arbitrary code execution inside your editor. Keep it up for the length of the
test and don't share it, or put
Cloudflare Access
(or equivalent) in front of the hostname before leaving it running.

Authoring Blueprint graphs

Blueprint node graphs are scriptable on UE 5.8+. Start with
ue_bp_graph_info, which returns the node object names every other tool takes
as a key, then ue_bp_add_call_function, ue_bp_add_branch,
ue_bp_add_custom_event, ue_bp_add_variable_node, or
ue_bp_add_node_by_name with ue_bp_list_palette for anything else. Wire with
ue_bp_connect, set literals with ue_bp_set_pin_value. Event nodes are
addressed by the alias event:ReceiveBeginPlay.

EdGraph.Nodes is still protected and pins are still unexposed — the route is
unreal.BlueprintGraphEditor, which edits the graph from the outside the way
the editor does. Details in docs/UNREAL-NOTES.md.

Check ue_status → capabilities.blueprint_graph_authoring first. On an
engine without that API the tools fail with an explanation, and the older route
still applies: put the logic in a C++ parent class. The Blueprint stays the
container for components and tweakable values; the behaviour is inherited.

ue_cpp_class_create      # writes the class, and the whole C++ module if the
                         # project was Blueprint-only
ue_editor_close
ue_build_start           # poll ue_build_status until running=false
ue_editor_open
ue_reparent_blueprint    # the Blueprint now inherits the behaviour

Blueprint variables whose names match a UPROPERTY on the new parent are
absorbed by it, so values set in the editor survive the move. Functions marked
BlueprintCallable become callable from the graph — an agent can build the
vocabulary the designer then wires up by hand.

Material graphs are fully scriptable too: ue_create_material really does
create and connect the nodes.

Other limits

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, or install
a folder/zip you already downloaded yourself (preset_fab_install).

Configuration

Variable	Default	Purpose
`UE_MCP_TRANSPORT`	`auto`	`auto`, `pyremote` (native channel) or `remotecontrol` (HTTP)
`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_PROJECT`	—	Which project to drive when several editors are open
`UE_MCP_MULTICAST_GROUP` / `_PORT`	`239.0.0.1` / `6766`	Discovery endpoint for the native channel
`UE_MCP_MULTICAST_BIND`	`0.0.0.0`	Interface the discovery ping goes out of — set it when several adapters (VPN, WSL, Hyper-V) hide the editor
`UE_MCP_MULTICAST_TTL`	`0`	Keeps discovery on this machine. Raising it exposes arbitrary code execution to the network
`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
`UE_MCP_HTTP`	—	`1` serves over HTTP instead of stdio, same as `--http`. Distinct from `UE_MCP_TRANSPORT`, which picks the channel to the editor
`UE_MCP_HTTP_PORT`	`8000`	Port the HTTP server listens on. Distinct from `UE_MCP_PORT`, which is Remote Control's
`UE_MCP_ALLOWED_HOSTS`	`*`	Comma-separated `Host` allowlist in HTTP mode. The default accepts any host because a tunnel's public hostname isn't knowable in advance; set it to lock the server to a known domain

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/. See
CONTRIBUTING.md for the conventions worth knowing.

ue_side.py is installed into the running editor as a module and keyed by a
hash of its source, so editor-side changes take effect on the next call without
restarting the server — and every other call is just a small snippet that
imports it. 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`
`ModuleNotFoundError: No module named 'mcp.server.fastmcp'`	`mcp` 2.x is installed; this server targets the 1.x line. `pip install "mcp<2"` — reinstalling the package does it for you

Licence

MIT — see LICENSE.

unreal-engine-mcp