Cognitive models of software comprehension are potential sources of theoretical knowledge for tool designers. Although their use in analysis of existing tools is fairly wellestablished, the literature has shown only limited use of such models for directly developing design ideas. This paper suggests a way of utilizing existing cognitive models of software comprehension to generate design goals and suggest design strategies early in the development cycle. A crucial part of our method is a scheme for explaining the value of tool features by describing the mechanisms that are presumed to underly the expected improvements in task performance.