It is widely agreed that mobile agents in conjunction with WWW technology will provide the technical foundation for future electronic commerce. A prerequisite for the use of mobile agents in a commercial environment is, that agents have to be executed reliable, independent of communication and node failure. In this paper, we first present a recently proposed fault-tolerant protocol to ensure the exactly-once execution of an agent by monitoring the agents execution. With this protocol, agents are performed in so-called stages. Each stage consists of a number of nodes. One of these nodes executes the agent while the other nodes monitor the execution. The main focus of this paper is the construction of stages. In particular, we will investigate how the number of nodes per stage influence the probability of an agent to be blocked due to failures and which nodes should be selected when forming a stage to minimize the overhead caused by the protocol. Also a flexible itinerary concept is prop...