In this paper, the radical view that transparent equipment is the result of an ecological assembly between tool users and physical aspects of the world is critically assessed. According to this perspective, tool users are normally viewed as plastically organized hybrid agents. In this view, such agents are able to interact with tools (artefacts or technologies) in ways that are opportunistic and fully locked to the local task environment. This intimate and flexible interaction would provide grounds for the thesis that (...) cognitive agents and tools constitute literal extended cognitive systems. By contrast, a revised understanding of tool use transparency will be attempted. In this perspective, the interplay between on-line and off-line thinking is understood in terms of a socially reified cognitive delegation that subsumes the advantages normally associated to the so-called ‘open-ended ecological controllers.’ Thus, the notion of transparent technologies can be explored on the basis of a derived or mediated cognitive delegation. This view will be complemented by the notion of communities of practice (CoP). Special sorts of CoP will be proposed as suitable and flexible cognitive environments for the development of tool transparency. (shrink)