uemcp 0.1.0

Open source MCP server that lets Claude drive Unreal Engine 5 with no plugin to compile

UEMCP

Drive Unreal Engine 5 with Claude. Nothing to install inside Unreal.

UEMCP is an open source MCP server by ATDev that connects Claude (Claude Code, Claude Desktop, or any MCP client) to a live Unreal Engine 5 editor. Spawn actors, build materials, author Blueprints, manage assets, fly the viewport camera, take screenshots, and run arbitrary editor Python, all from a conversation.

Why this one is different

Most Unreal MCP servers ship a C++ plugin you have to copy into your project and compile. UEMCP speaks Unreal's built-in Python remote execution protocol instead: the same multicast discovery and TCP command channel that ships with every copy of the engine. That means:

• Zero install on the Unreal side. No plugin to build, no project files to modify, no engine version matrix to chase.
• Works with vanilla UE 5.0 through 5.6, including Epic Games Launcher builds.
• Structured results, not log scraping. Every tool runs inside an error-capturing harness in the editor and returns clean JSON, with real Python tracebacks when something fails.
• Self-healing connection. Restart the editor mid-session and the next tool call reconnects automatically.
• An escape hatch. ue_python gives Claude the full unreal module for anything the 29 dedicated tools do not cover.

Quickstart

1. Set up Unreal (one time, about 30 seconds)

1. Open your project in Unreal Editor.
2. Edit > Plugins, search for Python Editor Script Plugin, enable it, restart when prompted.
3. Edit > Project Settings, search for Python, check Enable Remote Execution.

That is the entire Unreal-side setup.

2. Add the server to Claude

With uv installed:

Claude Code

claude mcp add unreal -- uvx uemcp

Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "unreal": {
      "command": "uvx",
      "args": ["uemcp"]
    }
  }
}

From a clone of this repo

uv run uemcp

3. Talk to your editor

"Spawn a point light 300 units up, make it warm orange at 8000 intensity, then screenshot the viewport."

"Find every static mesh asset with 'rock' in the name and scatter 20 of them in a rough circle around the origin."

"Create a BP_Collectible blueprint with a static mesh component and a sphere collision, set its mesh to the gold coin asset."

Tools

Group	Tools
Editor	ue_status, ue_python, ue_console_command, ue_project_info
Actors	ue_list_actors, ue_spawn_actor, ue_destroy_actor, ue_set_actor_transform, ue_set_actor_property, ue_get_actor
Assets	ue_search_assets, ue_asset_info, ue_import_asset, ue_create_folder, ue_duplicate_asset, ue_delete_asset, ue_save_all
Materials	ue_create_material, ue_create_material_instance, ue_assign_material
Blueprints	ue_create_blueprint, ue_add_component, ue_set_blueprint_default
Levels	ue_open_level, ue_new_level
Viewport	ue_set_camera, ue_get_camera, ue_focus_actor, ue_screenshot
Play	ue_play, ue_stop_play

Conventions: project content paths look like /Game/Props/SM_Chair, engine classes like /Script/Engine.PointLight. Distances are centimeters, rotations are [roll, pitch, yaw] in degrees, colors are [r, g, b] in 0..1.

Full parameter and return documentation for every tool: docs/tools.md.

How it works

Claude (MCP client)
   |  stdio (MCP)
   v
uemcp server (this package, plain Python)
   |  UDP multicast 239.0.0.1:6766  -> discovery ping/pong
   |  TCP command channel           -> JSON commands and results
   v
Unreal Editor (built-in Python remote execution)

Each tool builds a small Python snippet, wraps it in a harness that catches exceptions, runs it in the editor, and parses a sentinel-prefixed JSON line back out of the log output. The snippet builders are pure functions, so CI compiles every one of them without needing Unreal installed.

Configuration

Everything works with defaults when the editor and server are on the same machine. Override with environment variables when needed:

Variable	Default	Purpose
UEMCP_PROJECT	(first found)	Prefer a specific project when several editors are open
UEMCP_MULTICAST_GROUP	239.0.0.1	Discovery multicast group
UEMCP_MULTICAST_PORT	6766	Discovery port
UEMCP_COMMAND_HOST	127.0.0.1	Host the editor connects back to
UEMCP_COMMAND_TIMEOUT	120	Per-command timeout in seconds
UEMCP_DISCOVERY_TIMEOUT	2	Discovery wait in seconds

uemcp --project MyGame is shorthand for UEMCP_PROJECT=MyGame.

Security notes

UEMCP executes Python inside your editor process, by design. Treat it like giving Claude the editor's Python console:

• The remote execution protocol has no authentication. Keep the defaults (localhost command channel, multicast TTL 0) unless you fully control the network.
• Tools can modify and delete project content. Use source control on your project. You should be doing that anyway.
• Review what an agent did with ue_save_all withheld if you want a manual checkpoint before anything hits disk.

Documentation

Doc	What it covers
docs/setup.md	Detailed Unreal and client setup, multiple editors, remote machines
docs/tools.md	Full reference for all 31 tools: parameters, returns, examples
docs/architecture.md	The wire protocol, the snippet harness, and how to add a tool
docs/troubleshooting.md	Connection problems, firewalls, common tool errors
docs/cookbook.md	Prompt recipes: lighting rigs, greyboxing, asset audits

Development

git clone https://github.com/ATDev-Inc/uemcp
cd uemcp
uv sync
uv run pytest
uv run ruff check .

The test suite runs entirely without Unreal: protocol tests talk to a fake editor over real sockets, and every in-editor snippet is compile-checked.

Roadmap

• Sequencer tools (create level sequences, bind actors, render movies)
• Niagara system spawning and parameter control
• Landscape sculpting primitives
• True PIE (play-in-editor) control with input injection
• Asset thumbnails as MCP resources

PRs welcome. See CONTRIBUTING.md.

License

MIT. Copyright (c) 2026 ATDev.