After Nature reader Don Vande Krol emailed me this interesting article, link HERE. It was published in Minding Nature Vol. 8 No. 1 of January 2015 so it is fairly recent.
The argument of agential realism is that agency is not a property of objects (a predicate) but rather any objects' defining substantive core (the essential nature of any object in order to be an object, at all). Thus in strict sense agency (creativity) is that which makes possible any property whatsoever.
The only problem I see, though, when I read arguments like this is that one seems to lack a proper principle of individuation: that is, if activity/creativity is central to the identity of a thing rather than substances with properties, then other than activity one must account for what makes something uniquely an individual.