Why 'is the agent autonomous' is the wrong question
Decide which individual actions need approval. Drafting a reply, sending it and issuing a refund carry different risks, so one autonomy setting for the whole agent hides decisions your team needs to make.
The fix is to stop asking the question at the agent level and start asking it at the action level. A support agent might have twelve distinct actions it can take: look up an order, draft a reply, send a reply, issue a refund under $50, issue a refund over $50, escalate to a human, close a ticket, and so on. Each of those has a different reversibility profile and a different blast radius if it goes wrong. Treating them identically throws away the information you need to make a good decision.