Group assessment is an important collaborative learning structure for development of graduate teamwork competencies. However, group assessments are often associated with poorer learning outcomes due to highly negative student experiences involving tension and conflict. In this study, an online tool incorporating four strategic 'GATES' ("Team structure," "Communication," "Leadership," and "Situation monitoring/Mutual support") was designed to support the social processes required for team cohesion. The 'GATES' tool was evaluated using mixed methods in an observational, correlational (cross-sectional) study of 693 undergraduate and post-graduate university students and five academics in five Allied Health university courses with a group assessment task. Participants completed two anonymous questionnaires (previous experiences and current experiences) that generated both quantitative and qualitative data. In the first, 95.19% (178/187) of respondents reported a previous group assessment experience, and the experience was negative for 19.1% (34/178) of these students, with 85.3% (29/34) attributing this to group member behaviour. All academics reported issues with previous group assessments they had delivered. Of the students who used the tool (n = 52), there was no statistically significant association between gender, CALD status, or age with group assessment experience. However, 56.9% (29/52) of students and all five academics found the tool useful for getting the group started early, and for managing team issues. The tool appeared most helpful with organisation and planning than in managing team issues, potentially due to the tool negating issues before they arose. Overall, our study's findings indicate that 'GATES' keeps students on track and provides timely support during the team management process.