Agent skill

unreal-development

Unreal Engine integration skill for C++/Blueprint development, actor lifecycle management, plugin development, and editor automation. Enables LLMs to interact with Unreal Editor through MCP servers for level manipulation, Blueprint generation, and automated workflows.

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Install this agent skill to your Project

npx add-skill https://github.com/a5c-ai/babysitter/tree/main/library/specializations/game-development/skills/unreal-development

SKILL.md

Unreal Development Skill

Comprehensive Unreal Engine development integration for AI-assisted game creation, editor automation, and project management.

Overview

This skill provides capabilities for interacting with Unreal Engine projects, including C++ development, Blueprint visual scripting, actor management, and build automation. It leverages the Unreal MCP ecosystem for direct editor integration when available.

Capabilities

Project Management

  • Create and configure Unreal projects
  • Manage project settings (Project Settings, DefaultEngine.ini, etc.)
  • Configure plugin dependencies
  • Set up module structure for code organization

C++ Development

  • Generate Actor and Component classes with proper UCLASS macros
  • Create UObject subclasses with reflection support
  • Implement interfaces (UInterface)
  • Write custom Editor modules
  • Generate unit tests using Automation Framework

Blueprint Visual Scripting

  • Generate Blueprint classes from specifications
  • Create Blueprint function libraries
  • Design Blueprint interfaces
  • Build reusable Blueprint macros
  • Generate data-only Blueprints

Actor and Component System

  • Create and modify Actors programmatically
  • Design component hierarchies
  • Implement tick and lifecycle management
  • Set up actor replication for multiplayer

Level Design

  • Create and modify levels
  • Place actors and configure properties
  • Set up level streaming
  • Configure World Partition settings

Build System

  • Configure build settings for multiple platforms
  • Create build scripts using BuildGraph
  • Set up CI/CD pipelines
  • Manage platform-specific configurations

Prerequisites

Unreal Engine Installation

  • Unreal Engine 5.0 or higher recommended
  • Visual Studio 2022 with C++ game development workload
  • .NET 6.0 SDK for tooling

MCP Server (Recommended)

For direct Unreal Editor integration:

json
{
  "mcpServers": {
    "unreal": {
      "command": "python",
      "args": ["-m", "unreal_mcp"],
      "env": {
        "UNREAL_PROJECT_PATH": "/path/to/project.uproject"
      }
    }
  }
}

Alternative MCP servers:

  • UnrealMCP (kvick-games) - TCP server with JSON commands
  • unreal-mcp (chongdashu) - Natural language control
  • Unreal_mcp (ChiR24) - C++ Automation Bridge

Usage Patterns

Creating an Actor Class (C++)

cpp
// MyCharacter.h
#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Character.h"
#include "MyCharacter.generated.h"

UCLASS()
class MYGAME_API AMyCharacter : public ACharacter
{
    GENERATED_BODY()

public:
    AMyCharacter();

protected:
    virtual void BeginPlay() override;
    virtual void Tick(float DeltaTime) override;
    virtual void SetupPlayerInputComponent(class UInputComponent* PlayerInputComponent) override;

    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Movement")
    float MoveSpeed = 600.0f;

    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Movement")
    float JumpHeight = 420.0f;

    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    class UCameraComponent* CameraComponent;

    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Components")
    class USpringArmComponent* SpringArmComponent;

private:
    void MoveForward(float Value);
    void MoveRight(float Value);
    void StartJump();
    void StopJump();
};
cpp
// MyCharacter.cpp
#include "MyCharacter.h"
#include "Camera/CameraComponent.h"
#include "GameFramework/SpringArmComponent.h"
#include "GameFramework/CharacterMovementComponent.h"

AMyCharacter::AMyCharacter()
{
    PrimaryActorTick.bCanEverTick = true;

    // Create spring arm
    SpringArmComponent = CreateDefaultSubobject<USpringArmComponent>(TEXT("SpringArm"));
    SpringArmComponent->SetupAttachment(RootComponent);
    SpringArmComponent->TargetArmLength = 400.0f;
    SpringArmComponent->bUsePawnControlRotation = true;

    // Create camera
    CameraComponent = CreateDefaultSubobject<UCameraComponent>(TEXT("Camera"));
    CameraComponent->SetupAttachment(SpringArmComponent);

    // Configure movement
    GetCharacterMovement()->MaxWalkSpeed = MoveSpeed;
    GetCharacterMovement()->JumpZVelocity = JumpHeight;
}

void AMyCharacter::BeginPlay()
{
    Super::BeginPlay();
}

void AMyCharacter::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);
}

void AMyCharacter::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
{
    Super::SetupPlayerInputComponent(PlayerInputComponent);

    PlayerInputComponent->BindAxis("MoveForward", this, &AMyCharacter::MoveForward);
    PlayerInputComponent->BindAxis("MoveRight", this, &AMyCharacter::MoveRight);
    PlayerInputComponent->BindAction("Jump", IE_Pressed, this, &AMyCharacter::StartJump);
    PlayerInputComponent->BindAction("Jump", IE_Released, this, &AMyCharacter::StopJump);
}

void AMyCharacter::MoveForward(float Value)
{
    if (Value != 0.0f)
    {
        const FRotator Rotation = Controller->GetControlRotation();
        const FRotator YawRotation(0, Rotation.Yaw, 0);
        const FVector Direction = FRotationMatrix(YawRotation).GetUnitAxis(EAxis::X);
        AddMovementInput(Direction, Value);
    }
}

void AMyCharacter::MoveRight(float Value)
{
    if (Value != 0.0f)
    {
        const FRotator Rotation = Controller->GetControlRotation();
        const FRotator YawRotation(0, Rotation.Yaw, 0);
        const FVector Direction = FRotationMatrix(YawRotation).GetUnitAxis(EAxis::Y);
        AddMovementInput(Direction, Value);
    }
}

void AMyCharacter::StartJump()
{
    Jump();
}

void AMyCharacter::StopJump()
{
    StopJumping();
}

Creating a Data Asset (C++)

cpp
// EnemyDataAsset.h
#pragma once

#include "CoreMinimal.h"
#include "Engine/DataAsset.h"
#include "EnemyDataAsset.generated.h"

UENUM(BlueprintType)
enum class EEnemyType : uint8
{
    Melee,
    Ranged,
    Boss
};

UCLASS(BlueprintType)
class MYGAME_API UEnemyDataAsset : public UPrimaryDataAsset
{
    GENERATED_BODY()

public:
    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Basic Info")
    FString EnemyName;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Basic Info")
    EEnemyType EnemyType;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Stats")
    float MaxHealth = 100.0f;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Stats")
    float MoveSpeed = 300.0f;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Combat")
    float AttackDamage = 10.0f;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Combat")
    float AttackRange = 150.0f;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Visuals")
    TObjectPtr<USkeletalMesh> Mesh;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Visuals")
    TObjectPtr<UAnimBlueprint> AnimBlueprint;

    // UPrimaryDataAsset interface
    virtual FPrimaryAssetId GetPrimaryAssetId() const override;
};

Gameplay Ability System Example

cpp
// MyGameplayAbility.h
#pragma once

#include "CoreMinimal.h"
#include "Abilities/GameplayAbility.h"
#include "MyGameplayAbility.generated.h"

UCLASS()
class MYGAME_API UMyGameplayAbility : public UGameplayAbility
{
    GENERATED_BODY()

public:
    UMyGameplayAbility();

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Ability")
    float CooldownDuration = 1.0f;

    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = "Ability")
    float ManaCost = 10.0f;

protected:
    virtual void ActivateAbility(
        const FGameplayAbilitySpecHandle Handle,
        const FGameplayAbilityActorInfo* ActorInfo,
        const FGameplayAbilityActivationInfo ActivationInfo,
        const FGameplayEventData* TriggerEventData) override;

    virtual void EndAbility(
        const FGameplayAbilitySpecHandle Handle,
        const FGameplayAbilityActorInfo* ActorInfo,
        const FGameplayAbilityActivationInfo ActivationInfo,
        bool bReplicateEndAbility,
        bool bWasCancelled) override;
};

Integration with Babysitter SDK

Task Definition Example

javascript
const unrealActorTask = defineTask({
  name: 'unreal-actor-generation',
  description: 'Generate Unreal Engine Actor class',

  inputs: {
    actorType: { type: 'string', required: true }, // Character, Pawn, Actor
    className: { type: 'string', required: true },
    components: { type: 'array', required: true },
    outputPath: { type: 'string', required: true }
  },

  outputs: {
    headerPath: { type: 'string' },
    sourcePath: { type: 'string' },
    success: { type: 'boolean' }
  },

  async run(inputs, taskCtx) {
    return {
      kind: 'skill',
      title: `Generate Unreal Actor: ${inputs.className}`,
      skill: {
        name: 'unreal-development',
        context: {
          operation: 'generate_actor',
          actorType: inputs.actorType,
          className: inputs.className,
          components: inputs.components,
          outputPath: inputs.outputPath
        }
      },
      io: {
        inputJsonPath: `tasks/${taskCtx.effectId}/input.json`,
        outputJsonPath: `tasks/${taskCtx.effectId}/result.json`
      }
    };
  }
});

MCP Server Integration

Available MCP Tools (via unreal-mcp)

Tool Description
unreal_spawn_actor Spawn actor in level
unreal_modify_actor Modify actor properties
unreal_create_blueprint Generate Blueprint class
unreal_compile Trigger hot reload/compile
unreal_build Build for target platform
unreal_run_automation Execute automation tests
unreal_query_level Get level structure
unreal_python_exec Execute Unreal Python command

Configuration

json
{
  "mcpServers": {
    "unreal": {
      "command": "python",
      "args": ["-m", "unreal_mcp"],
      "env": {
        "UNREAL_PROJECT_PATH": "C:/Projects/MyGame/MyGame.uproject",
        "UNREAL_ENGINE_PATH": "C:/Program Files/Epic Games/UE_5.3"
      }
    }
  }
}

Best Practices

  1. UCLASS Macros: Always use appropriate specifiers (BlueprintType, Blueprintable, etc.)
  2. Property Specifiers: Use EditAnywhere/VisibleAnywhere and BlueprintReadWrite/BlueprintReadOnly correctly
  3. Replication: Mark replicated properties with UPROPERTY(Replicated)
  4. Memory Management: Use TObjectPtr for object pointers, avoid raw pointers
  5. Modules: Organize code into logical modules with clear dependencies
  6. Tick Optimization: Only enable tick when necessary, use Timers for periodic tasks

Platform Considerations

Platform Key Considerations
PC Full feature support, shader model 5+
Console Memory budgets, certification requirements
Mobile Simplified rendering, thermal management
VR Frame rate requirements, motion sickness prevention

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