Responsiveness as a concept of computer science refers to the specific ability of a system or functional unit to complete assigned tasks within a given time. For example, it would refer to the ability of an artificial intelligence system to understand and carry out its tasks in a timely fashion.
In the Reactive principle, Responsiveness is one of the fundamental criteria along with resilience, elasticity and message driven.
It is one of the criteria under the principle of robustness (from a v principle). The other three are observability, recoverability, and task conformance.