public static class ЛютыйФреймворк
{
    public static T GetAttribute<T>(this Type type, string propertyName)
        where T : Attribute
    {
        return type.GetProperty(propertyName)
            .GetCustomAttributes(typeof(T))
            .Cast<T>()
            .First();
    }
}

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
	// MetadataParameters содержит данные об именах свойств и типах.
	var mp = parameter as MetadataParameters;

	var modelPropertyInfo = mp.ModelType.GetProperty(mp.ModelProperty);
	if (modelPropertyInfo == null)
		return null;

	var attribute = modelPropertyInfo
		.GetCustomAttributes(true)
		.Cast<Attribute>()
		.FirstOrDefault(memberInfo => memberInfo.GetType() == mp.AttributeType);
	if (attribute == null)
		return null;

	var attributePropertyInfo = attribute.GetType().GetProperty(mp.AttributeProperty);
	if (attributePropertyInfo == null)
		return null;

	CultureInfo ci = Thread.CurrentThread.CurrentUICulture;

	var attributePropertyValue = attributePropertyInfo.GetValue(
		attribute,
		System.Reflection.BindingFlags.Default,
		null,
		new object[] { },
		ci);

	return attributePropertyValue;
}

<StackPanel Orientation="Horizontal">
    <TextBlock Text="{my:PropertyDescriptionMetadata {x:Type my:MyType}, MyProperty}"/>
    <TextBox Text="{Binding MyProperty}"/>
</StackPanel>

<TextBlock 
  <TextBlock.Text>
    <Binding
      Mode="OneWay"
      Converter="{StaticResource metadataConverter}">
      <Binding.ConverterParameter>
        <Converters:MetadataParameters
          ModelType="{x:Type SettingsModels:Common}"
          ModelProperty="ExceedThreshold"
          AttributeType="{x:Type Attributes:NameDescriptionAttribute}"
          AttributeProperty="Name" />                            
      </Binding.ConverterParameter>
    </Binding>
  </TextBlock.Text>
</TextBlock>