With the advent of an Internet of Services, requirements arise for new or repurposed channels to offer, sell, moderate, and change services. A possible manifestation of such a channel is an internet-based service marketplace. Due to the complexity of service delivery between arbitrary providers and consumers the effective matching of offering and demand, as well as its delivery, is crucial. To narrow and focus the search and delivery process we consider context-awareness as a key requirement. Context-aware information systems are conscious of their environment, i.e. their relevant execution context and, thus, provide a better targeted application experience. As there is no universally accepted context description model, which explicates relevant context information, we gathered requirements on the basis of expert interviews. The interviews were performed with stakeholders from different organizational units to get a broad understanding of the key issues. The consolidated findings lead to a number of context categories.