Background: Specialist training bodies continue to devise innovative methods of gathering information on trainee workplace performance to meet the requirements of competency-based medical education. We reviewed recent innovations in workplace-based assessment (WBA) tools to identify strengths, weaknesses, and trade-offs inherent in their design and use. Methods: In this scoping review, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we systematically searched databases between 2009 and 2019 for WBA tools with novel characteristics not typically seen in traditional WBAs. These included innovations in rating scales, ways of collecting information, technological innovations, ways of triggering WBAs, and approaches to compiling and using information. Results: We identified 30 innovative WBA tools whose characteristics could be categorised into seven dimensions: frequency of assessment, granularity (unit of performance assessed), coverage of the curriculum, rating method, initiation of the WBA, information use, and incentives. These dimensions had multiple interdependencies and trade-offs, often balancing generating assessment data with available resources. Philosophical stance on assessment also influenced WBA choice, for example prioritising trainee-centred learning (i.e. initiation of WBA and transparency of assessment data), perceptions of assessment and feedback as burdensome or beneficial, and holistic vs reductionist views on assessment of performance. Conclusions: Our synthesis of the literature on innovative WBAs provides a framework for categorising tool characteristics across seven dimensions, systematically teasing apart the considerations in design and use of workplace assessments. It also draws attention to the trade-offs inherent in tool design and selection, and enables a more deliberate consideration of the tool characteristics most appropriate to the local context.