At what point does an AI agent become useful enough to trust with real work?

I keep seeing AI agents getting better at doing more things, but I am still wondering where people draw the line between a useful agent and a risky one. If an agent can complete a task most of the time but still needs a human to check the important parts, is that already good enough for production? Or do you think an agent should be almost completely reliable before giving it real work? What would make you comfortable trusting an AI agent with something important? Would love to hear from people actually using agents in real workflows.