UECortex

Native Unreal Engine 5 plugin that runs a full MCP (Model Context Protocol) server inside the Unreal Editor. Control your project directly from Claude Code, VS Code, or any MCP client — no Python sidecar, no Node.js process, no external dependencies.

142 tools across 15 categories. Pure C++ core, with a Python-backed dynamic tool layer.

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Quick Start

1. Install

Copy the UECortex folder into your project's Plugins/ directory and enable it in your .uproject:

{
  "Name": "UECortex",
  "Enabled": true
}

Reopen the project. The server starts automatically on editor launch.

2. Connect

Claude Code:

claude mcp add uecortex --transport http http://localhost:7777/mcp

VS Code (.vscode/mcp.json):

{ "servers": { "uecortex": { "url": "http://localhost:7777/mcp" } } }

Health check:

GET http://localhost:7777/health

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Tool Categories

Level & Actors

actor_spawn actor_spawn_on_surface actor_delete actor_duplicate actor_set_transform actor_set_property actor_get_properties actor_get_selected actor_list actor_find_by_name level_get_info line_trace viewport_focus viewport_set_camera console_command

Blueprints

blueprint_list blueprint_get_graph blueprint_add_node blueprint_connect_pins blueprint_set_property blueprint_compile blueprint_add_component ...

C++ Codegen

cpp_create_class cpp_add_property cpp_add_function cpp_hot_reload ...

Rendering

rendering_set_nanite rendering_set_lumen material_create material_set_parameter material_compile ...

Splines & Volumes

spline_create spline_add_point spline_get_info volume_create volume_set_bounds ...

PCG (requires PCG plugin)

pcg_create_graph pcg_add_node pcg_connect_pins pcg_get_graph pcg_list_node_types pcg_execute ...

Gameplay Ability System (requires GameplayAbilities plugin)

gas_create_ability gas_add_attribute_set gas_grant_ability gas_apply_effect gas_list_abilities ...

Niagara

niagara_list_systems niagara_create_system niagara_add_emitter niagara_set_parameter niagara_compile ...

Animation

anim_list_skeletons anim_list_skeletal_meshes anim_get_skeleton_bones anim_create_anim_blueprint anim_add_state_machine anim_add_state anim_get_anim_graph anim_compile_anim_blueprint ...

UMG Widgets

umg_list_widgets umg_create_widget umg_get_widget_tree umg_add_widget umg_set_text umg_set_canvas_slot umg_set_anchor umg_set_visibility umg_add_variable umg_compile_widget

Sequencer

seq_create seq_list seq_get_info seq_set_playback_range seq_add_actor_binding seq_add_transform_track seq_add_keyframe seq_add_camera_cut seq_add_spawnable_camera seq_add_visibility_track

Asset Management

asset_list asset_get_info asset_get_references asset_get_dependencies asset_move asset_copy asset_delete asset_create_folder asset_list_redirectors asset_fix_redirectors

Viewport & Input (Windows/macOS)

viewport_capture editor_input

viewport_capture captures the 3D viewport or the full editor window as a PNG image. editor_input simulates mouse clicks and keyboard input on the editor window — useful for driving UI flows like the Fab browser search bar.

Fab Marketplace

fab_login_status fab_search fab_get_asset

fab_login_status checks EOS login state (required for purchases). fab_search and fab_get_asset are dynamic Python tools — load them once per session:

# Via MCP or curl:
python_reload_tools_from_file  →  Scripts/fab_tools.json

Purchase consent policy: fab_get_asset is an information-only tool. Every response includes an explicit CONSENT REQUIRED notice. AI agents must never trigger a purchase, add-to-cart, or any payment action without explicit confirmation from the user.

Python & Dynamic Tools

python_exec python_exec_file python_check python_set_var python_get_var python_list_scripts python_register_tool python_unregister_tool python_list_dynamic_tools python_reload_tools_from_file

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Dynamic Tool Registration

Register new tools at runtime — no recompile needed:

{
  "name": "python_register_tool",
  "arguments": {
    "name": "my_custom_tool",
    "description": "Does something useful.",
    "code": "import unreal\nactors = unreal.get_editor_subsystem(unreal.EditorActorSubsystem).get_all_level_actors()\n_mcp_result = f'{len(actors)} actors in scene'"
  }
}

The tool immediately appears in tools/list and is callable like any built-in tool. Tools receive their arguments as _mcp_params (dict) and return a result by setting _mcp_result (string).

Load an entire library from a JSON file:

[
  { "name": "tool_a", "description": "...", "code": "..." },
  { "name": "tool_b", "description": "...", "code": "..." }
]

{ "name": "python_reload_tools_from_file", "arguments": { "file_path": "Scripts/MCPTools.json" } }

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Optional Plugin Dependencies

Some tool categories only activate when the corresponding plugin is enabled in your project:

Category	Plugin	How to enable
PCG	Procedural Content Generation	Enable in Plugins window
GAS	Gameplay Abilities	Enable in Plugins window

All other categories load unconditionally.

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Architecture

• Transport: HTTP + SSE on localhost:7777
• Protocol: MCP 2024-11-05 / JSON-RPC 2.0
• Engine version: UE 5.6+ (5.7 compatible)
• Module type: Editor plugin, PostEngineInit
• Threading: HTTP handlers run on the game thread tick — all UE API calls are direct, no AsyncTask wrappers

Module layout

Module	Contents
UECortex	Core server, router, registry, level/blueprint/rendering/spline/cpp tools, editor_input, viewport_capture, fab_login_status
UECortexPCG	PCG graph tools
UECortexGAS	Gameplay Ability System tools
UECortexNiagara	Niagara VFX tools
UECortexUMG	Widget Blueprint tools
UECortexAnim	Animation Blueprint + skeleton tools
UECortexAsset	Asset management tools
UECortexSequencer	Level Sequence / cinematics tools
UECortexPython	Python executor + dynamic tool registry