It really depends what you mean by designing UML diagrams. From my personal perspective, UML is mostly a communication language, so that certain abstract concep

It really depends what you mean by designing UML diagrams. From my personal perspective, UML is mostly a communication language, so that certain abstract concepts (class structures and hierarchies, message passing sequences, etc.) can be communicated using a common language. For example, if two people are to work on the same piece of code or two pieces of code that are to interact together, being able to sketch a quick class diagram or a sequence diagram so that both parties can understand what is happening is much easier than writing it in an unambiguous textual representation. If you're asking about designing UML diagrams for tools that will automagically generate your application from diagrams, then I think that's definitely a different question. I haven't looked at what the current state of the code generation tools are, but when I looked at it several years ago, it didn't look very promising.