Containment — the share of conversations that never reach a person — is the number everyone reports and the one most easily gamed.
A bot that hides the handover option has excellent containment and is actively damaging the business. On its own the number cannot distinguish the two cases.
Resolution rate: did the customer's problem get solved. Satisfaction, collected on bot conversations specifically. And handover rate with reasons, which tells you where it fails.
Resolution is harder to measure and worth the effort. Containment is easy to measure and worth very little.
There is no useful benchmark. It depends on your question mix and your boundaries.
Because hiding the handover improves it. Pair it with resolution and satisfaction.
Questions it could not answer. That is a content backlog your customers wrote.
Half an hour with your own data usually saves reading three of these. The guides will still be here afterwards.