Multi-agent systems technologies have been widely investigated as a promising approach for modelling and building distributed systems. However, the benefits of agents are not restricted to systems solely comprised of agents. This paper considers how to ease the task of developing agents that perceive information from asynchronously executing external systems, especially those producing data at a high frequency. It presents a design for a percept buffer that, when configured with domain-specific percept metadata and application-specific percept management policies, provides a generic but customisable solution. Three application case studies are presented to illustrate and evaluate the approach.