Which attributes? What are the "attributes" and why should the user care? The only thing the user of an object should care about is being able to do whatever he needs with the object, which may include getting and setting certain "observable" properties, while the methods take care of keeping the object in a consistent internal state.
The actual attribute stored internally by a circle object might turn out to be the perimeter, but that doesn't affect the circle's user at all, as long as he is able to get the radius, or whatever he needs, out of the object. If the user then wants to set or get the perimeter and the implementation turns out to be a trivial "accessor" because it happens to match the internal structure of the object, it doesn't make any difference and is not bad design.