Model-Based Testing (MBT) has attracted the attention of many industries and, hence, it has provided several approaches reported in the literature. The Software Engineering Lab (LES) at the Pontifical Catholic University of Rio de Janeiro has worked extensively on coordinating and carrying out tests of large-scale software systems developed (for web and desktop) for different domains (e.g. petroleum, e-commerce, etc). Based on this experience, an LES test group created a new test modeling language called UML Testing Profile for Coordination (UTP-C) to model relevant test data. However, to use the advantages of the new modeling, an appropriate test-modeling tool became necessary. Thus, this paper presents the RSA-MBT, a new plug-in developed for the Rational Software Architecture (RSA) tool, to generate a set of test artifacts from UTP-C diagrams.