Design notations play an important role in designing software. Agent UML (AUML), which extends the widelyused UML notation, has proposed a number of notations for modelling agent systems. Arguably the most influential of the AUML notations has been the sequence diagram for defining interaction patterns between agents. However, AUML is not precisely and formally defined, and there is very little in the way of tool support available. In this paper we describe initial steps at resolving these two issues: we precisely define the syntax of (a subset of) AUML by using a textual notation, and we describe a tool that takes a textual AUML protocol and automatically generates the standard graphical rendition.