Integration and mediation are two core functions that a cloud service broker needs to perform. The description of services involved plays a central role in this endeavour to enable services to be considered as commoditised utilities. We propose a conceptual framework for a cloud service broker based on two parts: a reference architecture for cloud brokers and a service description template that describes the mediated and integrated cloud services. Structural aspects of that template will be identified, formalised in an ontology and mapped onto a set of sublanguages that can be aligned to the cloud development and deployment process.