A galaxy model is a multidimensional model dedicated for XML document warehouses. It can be seen as a network of entities (i.e., dimensions) connected via nodes. After giving an overview of our four-steps semi-automated method for the generation of galaxy models which aims to build data marts from XML documents. This paper focuses on the software tool, called Galaxy-Gen that implements the proposed method. We illustrate the Galaxy-Gen functionalities and make its first assessment through two experiments. The first experiment is applied to a set of twenty XML documents taken from the academic domain. The second one addressed a set of 1691 XML documents issued from the Clef-2007 collection. The assessment is performed by comparing manual design galaxy models with those produced by the Galaxy-Gen tool. The results are very promising.