Abstract
Tools are vital to support the various activities that form the many tasks that are part of the program comprehension process. In order that these tools are used and useful it is necessary that they support the activities of the user. This support must complement the work methods and activities of the user and not hinder them. Whilst features of good tools have been identified tool builders do not always adhere them to. It is important to consider whether needs have changed, and if those desirable properties need augmenting or revising. From experience of maintaining and enhancing an existing program comprehension tool for the purposes of participating in a re-engineering activity many lessons on tool support have been learned.