The Agent Architecture Description (AAD) activity aims at providing precise indications on the architecture that should be adopted by agents. Indeed an agent architecture is at least defined by the set of roles that the agent should play and the minimal set of services that implement the capacities required by these roles. The association between Agents and Agent Roles allows the identification of the set of capacities that are required by Agent Role in order to be played by Agents. In this activity, a UML class diagram is used to describe agents and their capacities realizations in terms of attributes and methods.