The change that matters is giving the system tools and the permission to use them, which converts a conversation from an explanation into a transaction. When a customer asks to change a delivery address, the assistant looks up the order, confirms it is still in a state where the change is possible, makes the update in the system that owns it, and gives back a reference the customer can quote. The conversation was the interface, and the work was actually done, which is the entire difference between a support cost and a support saving.
The second change is grounding, which means the assistant answers from your material rather than from general knowledge. Your policies, product documentation, pricing rules, and past resolutions are retrieved at the moment of the question and the answer is built from them, with a link back to the source so a person can verify it. This is what makes the difference between an assistant that is confidently wrong about your returns window and one that quotes it correctly because it just read it.
The third change is knowing when to stop, and it is the one most implementations skip. We build an explicit escape route so the assistant recognises the questions it should not attempt, whether that is a complaint, an unusual account situation, or anything involving money and entitlements, and hands over to a person with the conversation summarised so the customer does not have to start again. Handling that transition well does more for customer satisfaction than any improvement in the model.