This article explores Australian general practitioners’ (GPs) views on a novel electronic decision support (EDS) tool being developed for cardiovascular disease management. We use Timmermans and Berg’s technology-in-practice approach to examine how technologies influence and are influenced by the social networks in which they are placed. In all, 21 general practitioners who piloted the tool were interviewed. The tool occupied an ill-defined middle ground in a dialectical relationship between GPs’ routine care and factors promoting best practice. Drawing on Lipsky’s concept of ‘street-level bureaucrats’, the tool’s ability to process workloads expeditiously was of greatest appeal to GPs. This feature of the tool gave it the potential to alter the structure, process and content of healthcare encounters. The credibility of EDS tools appears to be mediated by fluid notions of best practice, based on an expert scrutiny of the evidence, synthesis via authoritative guidelines and dissemination through trusted and often informal networks. Balanced against this is the importance of ‘soft’ forms of knowledge such as intuition and timing in everyday decision-making. This resonates with Aristotle’s theory of phronesis (practical wisdom) and may render EDS tools inconsequential if they merely process biomedical data. While EDS tools show promise in improving health practitioner performance, the socio-technical dimensions of their implementation warrant careful consideration.