The development of Knowledge Discovery in Databases (KDD) projects in collaborative and distributed environments requires facilities to search for, choose, set-up, compose and execute suitable data manipulation tools. This implies the necessity to explicitly represent and annotate different kinds of information about tools, data and their characteristics. In this framework, we are developing a serviceoriented support platform called Knowledge Discovery in Databases Virtual Mart. In this paper we discuss the design and implementation of the UDDI service broker, a core element of the platform. We analyze the information needed to describe a tool in our platform, showing limitations of the present UDDI standard. Then, we present our solution to overcome such limitations and to extend UDDI broker capabilities.