The requirement for Australian initial teacher education (ITE) providers to administer a Teaching Performance Assessment (TPA) highlights a tension between policymaking directives and academic independence. It has raised fears of entrenching simplistic notions of measurement and evidence into a professional field distinguished by its complex relationship with intellectual and academic labour. Drawing on focus group data and reflections of academics co-designing an Australian TPA, this study considers how intellectual labour intertwines with its operational field, wherein co-construction of knowledge, critical thinking, and reflection define both academic and teachers' work. Our analysis explains how education academics, as principle-designers of an assessment instrument, might also negotiate the intellectual premise of a TPA within their own ITE programs. We find that Australia's initial TPA policy framework has been mediated with ITE academics. This offers opportunities for building knowledge to understand more precisely the TPA in its contexts, including admissible evidence to measure classroom-readiness.