yes-ue-mcp

Native C++ Model Context Protocol (MCP) plugin for Unreal Engine 5.6+

yes-ue-mcp is a native C++ Unreal Engine plugin that implements the Model Context Protocol (MCP) over Streamable HTTP. It enables AI assistants like Claude, Cursor, Windsurf, and others to interact directly with the Unreal Editor.

Key Features:

• ✅ Zero Dependencies - Uses UE's built-in FHttpServerModule
• ✅ Cross-LLM Compatible - Works with Claude, Cursor, Windsurf, VS Code Copilot, Continue, OpenAI, and more
• ✅ Editor-Integrated - HTTP server runs directly in UE Editor, no separate process needed
• ✅ Extensible - Easy-to-use tool registration system for custom MCP tools

1. Clone into your project's Plugins directory:

cd YourProject/Plugins
git clone https://github.com/softdaddy-o/yes-ue-mcp.git

2. Regenerate project files and build your project

3. Enable the plugin in your .uproject file or via Editor → Plugins

The plugin starts an HTTP server on localhost:8080/mcp. Configure in Config/DefaultYesUeMcp.ini:

[/Script/YesUeMcpEditor.McpServerSettings]
; HTTP server port (default: 8080)
; Change this if running multiple UE instances
ServerPort=8080

; Auto-start server when editor opens
bAutoStartServer=true

; Bind address (default: localhost for security)
BindAddress=127.0.0.1

Tip: When running multiple UE projects, set a different ServerPort for each project (e.g., 8080, 8081, 8082).

Claude Code CLI:

claude mcp add --transport http unreal-engine http://localhost:8080/mcp

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "unreal-engine": {
      "url": "http://localhost:8080/mcp"
    }
  }
}

Cursor (.cursor/mcp.json):

{
  "mcpServers": {
    "unreal-engine": {
      "url": "http://localhost:8080/mcp"
    }
  }
}

VS Code Continue (.continue/config.json):

{
  "mcpServers": [{
    "name": "unreal-engine",
    "transport": { "type": "http", "url": "http://localhost:8080/mcp" }
  }]
}

30 tools total (10 read + 20 write/modify tools)

Latest additions:

• v1.12.0: Enhanced trigger-live-coding with synchronous wait and compilation results
• v1.11.0: trigger-live-coding - Trigger Live Coding compilation for C++ changes
• v1.10.0: run-python-script - Execute Python scripts in Unreal Editor with argument passing
• v1.9.0: Dynamic reflection support for materials, nodes, and assets
• v1.8.0: StateTree query and modification tools

Note: This README shows legacy tool documentation. For the current consolidated tool architecture, see .claude/CLAUDE.md which includes:

• Consolidated read tools (query-blueprint, query-asset, query-material, etc.)
• Write tools (set-property, add-graph-node, create-asset, etc.)
• StateTree tools (query-statetree, add-statetree-state, etc.)
• Scripting tools (run-python-script)
• Build tools (trigger-live-coding)

Execute Python scripts in Unreal Editor's Python environment.

Parameters:

• script (string, optional) - Inline Python code
• script_path (string, optional) - Path to Python script file
• arguments (object, optional) - Arguments accessible via unreal.get_mcp_args()

Requirements: PythonScriptPlugin must be enabled

Example:

{
  "script": "import unreal\nprint(unreal.SystemLibrary.get_project_name())",
  "arguments": {"asset_path": "/Game/MyAsset"}
}

Complete Blueprint structure analysis including parent class, functions, variables, and components.

Parameters:

• asset_path (string, required) - Blueprint asset path (e.g., /Game/Blueprints/BP_Character)

Returns: JSON with complete Blueprint metadata

List all functions with signatures, parameters, return types, and metadata.

Parameters:

• asset_path (string, required) - Blueprint asset path
• function_filter (string, optional) - Filter by function name (wildcards supported)

Returns: Array of function definitions with full signatures

List all variables with types, default values, replication settings, and metadata.

Parameters:

• asset_path (string, required) - Blueprint asset path
• variable_filter (string, optional) - Filter by variable name (wildcards supported)

Returns: Array of variables with types and default values

Get component hierarchy with transforms and attachment relationships.

Parameters:

• asset_path (string, required) - Blueprint asset path
• include_transforms (boolean, optional) - Include component transforms (default: true)

Returns: Component tree with hierarchy and transforms

Read complete Blueprint graph structure including all nodes, connections, and pin data.

Parameters:

• asset_path (string, required) - Blueprint asset path
• graph_name (string, optional) - Specific graph name
• graph_type (string, optional) - Filter: event, function, or macro
• include_positions (boolean, optional) - Include node X/Y positions (default: false)

Returns: All graphs with nodes, pins, and connections

Get detailed information about a specific Blueprint node by GUID.

Parameters:

• asset_path (string, required) - Blueprint asset path
• node_guid (string, required) - Node GUID to inspect

Returns: Full node details with pins and connections

Read CDO (Class Default Object) property values from Blueprint.

Parameters:

• asset_path (string, required) - Blueprint asset path
• property_filter (string, optional) - Filter by property name (wildcards supported)
• category_filter (string, optional) - Filter by property category

Returns: All property defaults with types, categories, and flags

List actors in the currently open level with filtering options.

Parameters:

• class_filter (string, optional) - Filter by actor class (wildcards supported)
• folder_filter (string, optional) - Filter by World Outliner folder path
• tag_filter (string, optional) - Filter by actor tag
• include_hidden (boolean, optional) - Include hidden actors (default: false)
• include_components (boolean, optional) - Include component list (default: false)
• include_transform (boolean, optional) - Include transforms (default: true)
• limit (integer, optional) - Max results (default: 100)

Returns: Array of actors with optional transforms and components

Deep inspection of a specific actor in the level.

Parameters:

• actor_name (string, required) - Actor name or label to inspect
• include_properties (boolean, optional) - Include all properties (default: true)
• include_components (boolean, optional) - Include component details (default: true)

Returns: Complete actor details with properties and component hierarchy

Query project configuration settings.

Parameters:

• section (string, optional) - Section to query: input, collision, tags, maps, or all (default: all)

Returns: JSON with requested configuration sections:

• input: Action/axis mappings with keys and modifiers
• collision: Profiles, channels, and responses
• tags: Gameplay tag sources and settings
• maps: Default maps and game modes

Browse class inheritance tree showing parents and children.

Parameters:

• class_name (string, required) - Class to inspect (e.g., AActor, UActorComponent)
• direction (string, optional) - parents, children, or both (default: both)
• include_blueprints (boolean, optional) - Include Blueprint subclasses (default: true)
• depth (integer, optional) - Max inheritance depth (default: 10)

Returns: Class hierarchy with parent chain and child classes

Read DataTable and DataAsset contents.

Parameters:

• asset_path (string, required) - DataTable or DataAsset path
• row_filter (string, optional) - Filter rows by name (wildcards supported, DataTable only)

Returns:

• DataTable: All rows with field data
• DataAsset: All properties with values

Search assets by name, class, or path with wildcard support.

Parameters:

• pattern (string, optional) - Search pattern (wildcards supported)
• class_filter (string, optional) - Filter by asset class
• path_filter (string, optional) - Filter by asset path
• limit (integer, optional) - Max results (default: 100)

Returns: Array of matching assets with paths and types

┌──────────────────┐  HTTP POST   ┌──────────────────────────────┐
│  Claude / Cursor │ ──────────►  │  UE Editor                   │
│  Windsurf / etc  │  JSON-RPC    │  └─ YesUeMcp Plugin          │
│                  │ ◄──────────  │     └─ FHttpServerModule     │
│                  │   Response   │        (localhost:8080/mcp)│
└──────────────────┘              └──────────────────────────────┘

Modules:

• YesUeMcp (Runtime) - Core MCP protocol layer (JSON-RPC, tool registry)
• YesUeMcpEditor (Editor) - HTTP server + UE Editor tool implementations

See Docs/ToolDevelopment.md for a guide on creating custom MCP tools.

Requires Unreal Engine 5.6 or higher.

# Build with UnrealBuildTool
<UE>/Engine/Build/BatchFiles/Build.bat YourProjectEditor Win64 Development

MIT License - see LICENSE for details

Contributions are welcome! Please open an issue or submit a pull request.

• GitHub Repository
• Model Context Protocol
• MCP Specification