Multi-agent systems where the members are developed by parties with competing interests, and where there is no access to a member’s internal state, are often classified as ‘open’. The specification of protocols for open agent systems of this sort is largely seen as a design-time activity. Moreover, there is no support for run-time specification modification. Due to environmental, social, or other conditions, however, it is often required to revise the specification during the protocol execution. To address this requirement, we present an infrastructure for ‘dynamic’ protocol specifications, that is, specifications that may be modified at runtime by agents. The infrastructure consists of well-defined procedures for proposing a modification of the ‘rules of the game’ as well as decision-making over and enactment of proposed modifications. We evaluate proposals for rule modification by modelling dynamic specifications as metric spaces. Furthermore, we constrain...