The problem with this definition 'an agent that can do tasks animals or humans can perform' is that it's not clear what that would look like. If you produce a system that can be interacted with via text input only but is otherwise capable of doing everything a human can do in terms of information processing, is that AGI? Or does AGI imply a human-like embodied form? Why?

Sorry, your original comment sounded like you were asking what the acronym stood for, not the definition of Artificial General Intelligence.