Inspired by the 'material turn' in the social sciences, education scholars have engaged in discussions on various materialist modes of policy analysis for a long time now. This paper continues these discussions by experimenting with an agential realist re-reading of the instrumentation approach originally proposed by Lascoumes & Le Gales. Through an affirmative-diffractive methodology, the paper suggests that policy instruments can be conceptualized as socio-technical, entangled, and performative instruments that produce distinctive discursive-material effects by virtue of their particular capacities. This conceptualization continues key features of the original instrumentation approach, while contributing a concept of instrument capacities and amplifying the importance of the material and ontological character of the performative effects of policy instruments and their entanglement with policy content and wider sets of policies. By including the empirical case of higher education accreditation in the re-reading, the article offers an approach capable of analyzing how policy instruments contribute to the crafting of the ontological constitution of the university in alignment with the standards and practices produced by the accreditation instrument. The article suggests that the realities currently being invoked by instruments such as accreditation seem to reconfigure--and diminish--the very raison d'être of the university.