1. A method for evaluating compliance of a user interface design, the method comprising: constructing a hierarchy at a first application, wherein the constructing comprises: detecting an event at a client data processing system; identifying a user interface as being responsive to the event, the user interface being described in an interface description; selecting a first user interface element from the interface description; identifying a first attribute of the first user interface element; and adding the first user interface element and the first attribute of the first user interface element to the hierarchy responsive to determining that the first attribute is usable in a compliance testing; receiving, from the first application executing in the client data processing system, the hierarchy of elements of the user interface, wherein a second application presents the user interface including a set of user interface elements at the client data processing system, the interface description comprising an organization of the set of user interface elements according to a manner of presenting the set of user interface elements on the user interface, the hierarchy being distinct from the organization by excluding from the set of user interface elements a second subset of those user interface elements which are irrelevant to the accessibility feature, wherein the accessibility feature is configured according to a rule in a usability specification, for a user with a disability, to assist in interacting with the user interface; selecting a compliance rule from a set of compliance rules; evaluating, using a processor and a memory, whether an attribute associated with an element in the hierarchy meets a condition specified in the compliance rule; and reporting, responsive to the evaluating being negative, the user interface element as being non-compliant with the compliance rule.