Domain-specific tools for modeling and simulation (M&S) of computer network systems are aimed at simplifying the tasks of model developers and simulationists. In determining the extent to which a particular domain-specific M&S tool fits their needs, the developers must consider both how the tool can assist in the model development process, and how the tool may prevent or hinder them from achieving their objectives. We have considered two M&S tools in the domain of computer networks, IT Guru and the INET Framework, and some of the ways in which they affect various aspects of simulation model development, with emphasis on the verification and validation (V&V) process as applied to Net-Centric Enterprise Systems. We have developed a metric for evaluating a domain-specific M&S tool based on certain qualitative characteristics. We will demonstrate how this metric can be applied to evaluate IT Guru and INET, and also offer some observations on how the metric can be applied to other domains besides computer networking.