This paper presents an intelligent agent called ISCA that finds a reasonable configuration for a spacecraft given its mass and volume budgets. ISCA is integrated in a multi-agent mission architecture framework used for early mission concept studies, and must therefore trade fidelity against computational expense. ISCA uses a rule-based system to exhaustively search over combinations of launch vehicles and configurations generated using different stacking heuristics and rules of thumb. The least expensive combination is selected and used to estimate launch cost. The information is also fed back to several subsystem design modules such as attitude control to account for updated inertial properties, which leads to the need for iteration. Despite this being work in progress, the validation shown in this paper shows the promise of the rule-based approach to obtain good enough configurations in a fraction of a second. The integration of ISCA with a catalog-based CubeSat design tool shows how ISCA is also capable of producing realistic configurations if COTS or legacy components are used.