The Delphi technique is a qualitative research method for building group consensus and has been widely adopted in the development of guidance documents. Published Delphi studies vary considerably in methodological quality, yet no dedicated critical appraisal tool existed until the Delphi Critical Appraisal Tool (DCAT) was published in 2025. DCAT comprises four core items (anonymity, iteration, statistical summary and controlled feedback) and twelve additional items (justification for Delphi, type of Delphi, panelist expertise, panelist retention, preliminary work, design choices, survey questions, response items, pilot test, data analysis, transparent reporting and ethical issues) and represents the first discipline-independent critical appraisal tool for Delphi studies, applicable to study protocol development, peer review and published study appraisal. This article interprets the item structure and appraisal logic of DCAT, aiming to facilitate quality appraisal and methodological improvement of Delphi studies.