How to add InfoBox to my class?

So i found this: Inspector.Decorations.InfoBoxAttribute but there are no comments in the library and it seems that there is no documentation for this Attribute. Does anyone know how to use it? What order and visibleCheck are? I tried

  [Inspector.Decorations.InfoBox(1, "MyMessage")]
  public int test;

and

  [Inspector.Decorations.InfoBox(0, "MyMessage")]
  public int test;

but none works. My class inherits after Monobehaviour ofcourse. I tried moving it over the class but error said it is only valid on field declarations.