Various metrics exist for evaluating UML diagrams, including entropy-based ones like ours, which assess information content. They allow for judging certain features of the design that depend on the information content. This paper proposes the FBS24 use case diagram measure, which should ensure that the software architecture design consists of mature UML diagrams. Detecting an inappropriate (immature, unfinished) Use Case Diagram before the software development phase can stall the entire software development process until a mature UCD is developed. Currently, no indicators (metrics) show the maturity (or lack of applicability) of diagrams. Moreover, in most such software metrics, weights are selected arbitrarily, which leads to numerous anomalies. We show how to construct the measure most resistant to such anomalies. We also show how to check the correctness and usefulness of the constructed measure. As our measure is objective, it is suitable for remote work of distributed teams building IT systems.