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.

169 built-in tools across 17 categories, plus 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" } } }

Claude Desktop (claude_desktop_config.json):

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

Health check:

GET http://localhost:7777/health

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Tool Categories

Meta

Discover what's available before diving into the full tools list.

Tool	What it does
list_tool_groups	Lists all categories with tool counts and names

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Level & Actors

Spawn, move, delete, and inspect actors in the current level.

Tool	What it does
actor_spawn	Spawn an actor by class at a given location/rotation/scale
actor_spawn_on_surface	Spawn an actor snapped to the nearest surface below a point
actor_delete	Delete an actor from the level
actor_duplicate	Duplicate an actor with optional offset
actor_set_transform	Set an actor's position, rotation, and/or scale
actor_set_property	Set a property on an actor by name
actor_get_properties	Read all exposed properties of an actor
actor_get_selected	Get the currently selected actors in the editor
actor_list	List all actors in the level, with optional class filter
actor_find_by_name	Find an actor by label name
level_get_info	Get level name, world bounds, and actor count
line_trace	Cast a ray and return what it hits (location, normal, actor)
viewport_focus	Focus the editor viewport on an actor
viewport_set_camera	Set the editor camera position and rotation
console_command	Execute an Unreal console command

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Blueprints

Create and wire Blueprint assets programmatically.

Tool	What it does
blueprint_create	Create a new Blueprint class from a parent class
blueprint_add_component	Add a component (mesh, camera, audio, etc.) to a Blueprint
blueprint_set_component_property	Set a property on a Blueprint component
blueprint_set_cdo_property	Set a Class Default Object property
blueprint_set_inherited_component_property	Set a property on an inherited component
blueprint_add_variable	Add a typed variable to a Blueprint
blueprint_set_variable	Set the default value of a Blueprint variable
blueprint_add_function	Add a new function to a Blueprint
blueprint_add_event_node	Add an event node (BeginPlay, Tick, custom event, etc.)
blueprint_add_function_call	Add a function call node to a Blueprint graph
blueprint_connect_pins	Connect two pins in a Blueprint graph
blueprint_compile	Compile a Blueprint asset
blueprint_get_graph	Read the full node/pin/connection graph as JSON
blueprint_find_node	Find a node by class or title
blueprint_set_node_property	Set a property on a graph node
blueprint_spawn_in_level	Add a Blueprint actor to the current level
blueprint_create_input_action	Create an Enhanced Input action and bind it
blueprint_add_gamemode	Create a GameMode Blueprint and set it as the default

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C++ Code Generation

Generate C++ source files and trigger editor recompilation.

Tool	What it does
cpp_create_actor	Generate a new AActor subclass (.h + .cpp)
cpp_create_component	Generate a new UActorComponent subclass
cpp_create_interface	Generate a new UInterface
cpp_create_gas_ability	Generate a UGameplayAbility subclass
cpp_create_gas_effect	Generate a UGameplayEffect subclass
cpp_create_attribute_set	Generate a UAttributeSet subclass
cpp_add_include	Add a #include to an existing header
cpp_add_uproperty	Add a UPROPERTY to an existing class
cpp_add_ufunction	Add a UFUNCTION to an existing class
cpp_get_class_info	Read the properties and functions declared on a class
cpp_hot_reload	Trigger a hot reload of the project module
cpp_run_ubt	Run a full UnrealBuildTool compile

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Rendering & Materials

Control Lumen, Nanite, shadows, post-process, fog, sky, and materials at runtime.

Tool	What it does
render_set_lumen	Enable/disable Lumen GI and configure quality settings
render_get_lumen_settings	Read current Lumen settings
render_set_nanite	Enable/disable Nanite on a Static Mesh
render_get_nanite_settings	Read Nanite settings for a mesh
render_set_shadows	Configure shadow distance, cascades, and quality
render_set_post_process	Set post-process volume settings (bloom, AO, DOF, etc.)
render_get_post_process	Read current post-process settings
render_set_fog	Configure exponential height fog
render_set_sky_atmosphere	Configure the sky atmosphere component
render_set_sky_light	Set sky light intensity and source type
render_set_ambient_occlusion	Configure SSAO settings
render_get_materials	List materials assigned to a mesh
render_set_material	Assign a material to a mesh slot
render_set_material_param	Set a scalar or vector parameter on a material instance
render_create_material_instance	Create a Material Instance from a parent material

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Splines & Volumes

Build spline paths and place trigger/blocking volumes.

Tool	What it does
spline_create	Create a new Spline actor in the level
spline_add_point	Add a point to a spline
spline_modify_point	Move or change the tangent of an existing spline point
spline_query	Read all points and metadata from a spline
spline_attach_mesh	Attach a Static Mesh along a spline
volume_create	Create a volume actor (trigger, blocking, post-process, etc.)
volume_set_properties	Resize and reposition an existing volume

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PCG (requires Procedural Content Generation plugin)

Build and execute PCG graphs for procedural level population.

Tool	What it does
pcg_create_graph	Create a new PCG Graph asset
pcg_add_node	Add a node to a PCG graph
pcg_connect_pins	Connect two nodes in a PCG graph
pcg_disconnect_pins	Disconnect a pin connection
pcg_get_graph	Read the full PCG graph as JSON
pcg_get_node_params	Read the parameters on a PCG node
pcg_set_node_param	Set a parameter on a PCG node
pcg_set_graph_param	Set a graph-level parameter (exposed input)
pcg_list_node_types	List all available PCG node types
pcg_execute_graph	Trigger a PCG graph to regenerate
pcg_create_attribute_node	Create an attribute node with a given name/type
pcg_create_subgraph	Create a subgraph node referencing another PCG asset
pcg_place_volume	Place a PCG Volume in the level and assign a graph
pcg_place_seed_actor	Place a PCG seed actor for point-based generation

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Gameplay Ability System (requires GameplayAbilities plugin)

Wire up GAS components, abilities, attributes, and gameplay tags.

Tool	What it does
gas_add_ability_component	Add an Ability System Component to a Blueprint
gas_grant_ability	Grant a gameplay ability to an actor
gas_revoke_ability	Remove a granted ability from an actor
gas_get_abilities	List all abilities granted to an actor
gas_apply_effect	Apply a Gameplay Effect to an actor
gas_get_active_effects	List active effects on an actor
gas_get_attributes	Read all attribute values on an actor
gas_set_attribute	Set an attribute value directly
gas_add_gameplay_tag	Add a gameplay tag to an actor
gas_remove_gameplay_tag	Remove a gameplay tag from an actor
gas_get_gameplay_tags	List all gameplay tags on an actor
gas_list_registered_tags	List all gameplay tags registered in the project

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Niagara VFX

Spawn, configure, and control Niagara particle systems.

Tool	What it does
niagara_list_systems	List all Niagara System assets in the project
niagara_create_system	Create a new Niagara System asset
niagara_list_emitters	List emitters inside a Niagara System
niagara_get_parameters	Read user-exposed parameters on a Niagara System
niagara_set_parameter	Set a parameter value on a Niagara System asset
niagara_spawn_component	Spawn a Niagara component on an actor in the level
niagara_activate_component	Activate or deactivate a spawned Niagara component
niagara_set_component_parameter	Set a runtime parameter on a spawned Niagara component

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Animation

Build Animation Blueprints, state machines, and retarget animations across skeletons.

Inspection

Tool	What it does
anim_list_skeletons	List all Skeleton assets in the project
anim_list_skeletal_meshes	List all Skeletal Mesh assets
anim_list_anim_blueprints	List all Animation Blueprints
anim_list_sequences	List AnimSequences compatible with a given skeleton
anim_get_skeleton_bones	List every bone name and parent in a skeleton
anim_get_anim_graph	Inspect all graphs, states, and nodes in an AnimBP

Building Animation Blueprints

Tool	What it does
anim_create_anim_blueprint	Create a new Animation Blueprint for a skeleton
anim_add_state_machine	Add a State Machine node to the AnimGraph
anim_add_state	Add a named state to a State Machine
anim_set_state_animation	Assign an AnimSequence or BlendSpace to a state
anim_add_transition	Add a transition arrow between two states
anim_set_transition_condition	Wire a variable condition onto a transition rule (supports always_true)
anim_set_entry_state	Connect the Entry node to a named state in a State Machine
anim_compile_anim_blueprint	Compile and save an Animation Blueprint
anim_create_locomotion_setup	One-call full locomotion setup: SM + 5 states + transitions + EventGraph wiring

IK Retargeting (requires IKRig plugin)

Tool	What it does
ik_rig_assign_mesh	Assign a SkeletalMesh to an IK Rig (required first step)
ik_rig_set_retarget_root	Set the retarget root bone on an IK Rig
ik_rig_add_retarget_chain	Add a retarget chain (limb, spine, head, etc.)
ik_rig_remove_retarget_chain	Remove a retarget chain by name
ik_retarget_create	Create an IK Retargeter pairing two IK Rigs with auto chain-mapping
anim_retarget_batch	Batch-retarget a list of animations to a new skeleton

Maintenance

Tool	What it does
skeleton_fix_broken_references	Repair broken skeleton references across anim assets

Animation Blueprint workflow: add variable → add state machine → add states → assign animations → add transitions → compile → set transition conditions → compile again. Compile must happen before anim_set_transition_condition so the variable getter can resolve its type.

For standard locomotion, use anim_create_locomotion_setup to do all of the above in a single call (includes EventGraph wiring for Speed and IsInAir).

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UMG Widgets

Create and populate Widget Blueprint UIs.

Tool	What it does
umg_list_widgets	List all Widget Blueprint assets
umg_create_widget	Create a new Widget Blueprint
umg_get_widget_tree	Read the full widget tree as JSON
umg_add_widget	Add a widget (Text, Button, Image, etc.) to the tree
umg_set_text	Set the text content of a Text widget
umg_set_canvas_slot	Set position and size of a widget on a Canvas Panel
umg_set_anchor	Set anchor alignment on a Canvas Slot
umg_set_visibility	Show or hide a widget
umg_add_variable	Add a variable to a Widget Blueprint
umg_compile_widget	Compile a Widget Blueprint

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Sequencer

Build cinematic Level Sequences with camera cuts, tracks, and keyframes.

Tool	What it does
seq_create	Create a new Level Sequence asset
seq_list	List all Level Sequences in the project
seq_get_info	Read sequence duration, framerate, and track layout
seq_set_playback_range	Set the in/out point of a sequence
seq_add_actor_binding	Bind an actor to a sequence for animation
seq_add_transform_track	Add a transform (movement) track to a bound actor
seq_add_keyframe	Set a keyframe value at a given frame
seq_add_camera_cut	Add a camera cut section
seq_add_spawnable_camera	Add a new spawnable camera actor to the sequence
seq_add_visibility_track	Add a visibility track to a bound actor

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Asset Management

Browse, move, copy, delete, and migrate content browser assets.

Tool	What it does
asset_list	List assets in a folder (with optional class filter)
asset_get_info	Get metadata for an asset (class, path, size, dependencies)
asset_get_references	List assets that reference a given asset
asset_get_dependencies	List assets that a given asset depends on
asset_move	Move or rename an asset
asset_copy	Duplicate an asset to a new path
asset_delete	Delete an asset permanently
asset_create_folder	Create a new content browser folder
asset_list_redirectors	List all redirector assets in a path
asset_fix_redirectors	Consolidate and remove redirectors
asset_migrate	Migrate an asset and all dependencies to another project

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Viewport & Input

Capture screenshots and drive the editor UI programmatically.

Tool	What it does
viewport_capture	Capture the 3D viewport or full editor window as a PNG
viewport_focus	Focus the viewport on an actor
viewport_set_camera	Set the editor camera position and rotation
editor_input	Simulate mouse clicks and keyboard input on the editor window

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Fab Marketplace

Search and inspect assets from the Fab marketplace inside the editor.

Tool	What it does
fab_login_status	Check EOS login state (required before purchases)
fab_search	Search Fab for assets by keyword (dynamic — load once per session)
fab_get_asset	Get full details for a Fab asset by ID (dynamic — load once per session)

Load the dynamic tools once per session:

python_reload_tools_from_file  →  Scripts/fab_tools.json

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

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Python & Dynamic Tools

Execute Python in the editor context and register new tools at runtime without recompiling.

Tool	What it does
python_exec	Run a Python snippet in the editor's Python environment
python_exec_file	Run a Python script file from the project's Scripts folder
python_check	Check whether a Python expression evaluates without error
python_set_var	Store a named variable for use across python_exec calls
python_get_var	Read a stored variable
python_list_scripts	List available Python scripts in the Scripts folder
python_register_tool	Register a new MCP tool backed by a Python snippet
python_unregister_tool	Remove a dynamically registered tool
python_list_dynamic_tools	List all currently registered dynamic tools
python_reload_tools_from_file	Load a batch of tools from a JSON file

Example — register a tool at runtime:

{
  "name": "python_register_tool",
  "arguments": {
    "name": "count_actors",
    "description": "Count all actors in the current level.",
    "code": "import unreal\nactors = unreal.get_editor_subsystem(unreal.EditorActorSubsystem).get_all_level_actors()\n_mcp_result = f'{len(actors)} actors'"
  }
}

Tools receive their arguments as _mcp_params (dict) and return a result by assigning _mcp_result (string).

Batch load from a JSON file:

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

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Optional Plugin Dependencies

Some categories only activate when their plugin is enabled:

Category	Required Plugin	Enable via
PCG	Procedural Content Generation	Plugins window
GAS	Gameplay Abilities	Plugins window
Niagara	Niagara	Enabled by default in UE5
IK Retarget	IKRig	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/volume/cpp/viewport/fab/meta tools
UECortexAsset	Asset management tools
UECortexAnim	Animation Blueprint, skeleton, and state machine tools
UECortexIKRetarget	IK Rig setup and batch retarget tools (optional — requires IKRig)
UECortexUMG	Widget Blueprint tools
UECortexSequencer	Level Sequence / cinematics tools
UECortexPCG	PCG graph tools (optional — requires PCG plugin)
UECortexGAS	Gameplay Ability System tools (optional — requires GameplayAbilities)
UECortexNiagara	Niagara VFX tools
UECortexPython	Python executor + dynamic tool registration