Just a quick referencce on defining and using a custom bool like Attribute

BoolTypeAttribute.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace Savaged.Sandpit
{
    class Program
    {
        static void Main(string[] args)
        {
            var models = new List<IBaseModel>
            {
                new FirstModel(),
                new SecondModel()
            };

            foreach (var model in models)
            {
                var attribs = model.GetType()
                    .GetCustomAttributes(typeof(AtomicAttribute), true);

                bool isAtomic = attribs.FirstOrDefault() 
                    is AtomicAttribute attrib 
                    ? (bool)attrib : false;

                Console.WriteLine($"{model.GetType().Name} {Convert(isAtomic)} atomic");
            }
            Console.ReadLine();
        }

        static string Convert(bool value)
        {
            return value ? "is" : "is not";
        }
    }

    public class AtomicAttribute : Attribute
    {
        public AtomicAttribute()
        {
            Value = true;
        }

        public bool Value { get; }

        public static implicit operator bool(AtomicAttribute value)
        {
            if (value is null)
            {
                return false;
            }
            return value.Value;
        }

        public static explicit operator AtomicAttribute(bool value)
        {
            if (!value)
            {
                return null;
            }
            return new AtomicAttribute();
        }

    }

    public interface IBaseModel
    {
        string Name { get; set; }
    }

    public abstract class BaseModel : IBaseModel
    {
        public string Name { get; set; }
    }

    public class FirstModel : BaseModel
    {
    }

    [Atomic]
    public class SecondModel : BaseModel
    {
    }
}