While the Belief, Desire, Intention (BDI) framework is one of the most influential and appealing approaches to rational agent architectures, a gulf often exists between the high-level BDI model and its practical realisation. In contrast, the Concurrent METATEM language, being based upon executable formal specifications, presents a close link between the theory and implementation, yet lacks some of the features considered central to the representation of rational agents. In this paper, we introduce a hybrid approach combining the direct execution of Concurrent METATEM with elements of rationality from the BDI framework. We show how this system can capture a range of agent behaviours, while retaining many of the advantages of executable specifications.