This paper shows how language technologies such as the automatic generation of parsers for analyzing user actions and visual parsing can be applied to build a flexible tool specialized in complex specification tasks, namely the configuration of distributed applications. The central issue is to propose to structure the workspace through a syntax of user actions on one hand, and a syntax of visual representations on the other hand. From the tool designer side, this approach makes the core of the tool explicit through the grammar rules, and eases the generation of final code by simplifying verifications. From the user side, properties of the workspace generated from high level specifications increase the usability and improve the perception of the underlying semantics.