An agent with no guardrails will eventually do something you did not authorize.
The thing that makes an AI agent useful — that it can take actions, not just produce text — is also the thing that makes it risky. Give an agent a tool that can send an email, delete a record, move money, or publish something, and enough autonomy to use it, and it can eventually follow its own reasoning to a place you never anticipated. Not because the model is malicious, but because it is probabilistic and you cannot enumerate every path it might take. An agent without hard guardrails on its dangerous tools is not a productivity gain — it is an incident waiting for a quiet afternoon.