Summary: Resources management facilities, based on service level agreements, are needed in the Cloud in order to negotiate a collection of inter-connected and virtualized computers between resource providers and consumers. In this paper we present the architectural design of a system named Cloud Agency which aims to respond to this need and to offer added value to the existing Cloud services. This system is in charge to broker the collection of Cloud resources from different providers that fulfills at the best the requirements of user’s applications. The user is able to delegate to the Agency the necessary checks of the agreement fulfilment, the monitoring of resource utilization and eventually necessary re-negotiations.