To strengthen the motivation of learners, the professional training sector is focusing more and more on game-based learning. In this context, the authors have become interested in the design of Learning Role-Play Game (LRPG) scenarios. The aim of this article is to improve the designers' confidence in the validity of the game-based learning programs developed by providing a methodology and tools to support their choices. The first stage of this work is the creation of a grid to describe LRPG scenarios. This grid will serve to support the design methodology, the collecting and sharing of LRPG scenarios and components, and the operationalization of the scenarios designed. First, this article details the purpose of the authors' work. Then, it outlines the main characteristics of the description grid constructed mainly based on Klabbers' work and on the study of game mechanics. Furthermore, applications of the description grid in a design-support environment are discussed and future work is presented. (Contains 1 table and 2 figures.)