Description grammars represent a formalism for generating verbal descriptions of designs, used in conjunction with shape grammars. A description grammar constitutes a set of description rules that define a language of descriptions. A description grammar interpreter implements the mechanisms to interpret descriptions and description rules, apply description rules to descriptions to derive new descriptions, and generate the members of the corresponding language of descriptions. In this paper, we argue the need for the development of a (general) description grammar interpreter, offer a formal notation for descriptions and description rules, describe the representation and implementation of descriptions and description rules, and provide an example implemented using the description grammar interpreter.