Last month a Series A startup I know woke up to a $47,000 AWS bill. The month before it had been $6,000. Nobody did anything "wrong" — a new microservice quietly fanned every request out through a NAT Gateway, and at a few cents per GB processed, it added up fast. They found out on the 3rd of the following month, when the invoice landed. By then the money was already gone. Here is the uncomfortable truth: most teams only discover cost anomalies AFTER the fact. You log into Cost Explorer, you see the ugly hockey-stick graph, and you spend the next two days doing forensic archaeology on something that happened two weeks ago. Dashboards are rear-view mirrors. They tell you where you crashed, not that you were about to. What if the loop were flipped? Instead of a human remembering to check a dashboard, imagine an AI agent that: 1. Pulls the AWS Cost Explorer API every morning, grouped by service. 2. Computes a rolling 7-day baseline for each service and flags anything spiking more than ~20%. 3. Hands the raw numbers to Claude and asks it to reason about the likely cause — not just "spend went up," but "EC2-Other jumped 340%, this pattern is consistent with NAT Gateway data processing charges from a new workload." 4. Fires a Slack alert to your team channel with the service, the dollar delta, the percentage jump, Claude's diagnosis, and a recommended next action — before the bill lands. That is the difference between a threshold alarm and an agent. CloudWatch can tell you a number crossed a line. It cannot tell you why, and it cannot tell you what to do about it. Claude can look at "Lambda invocations up 1,200%, duration flat" and say "this looks like a retry storm or an event-source loop, check for a Lambda writing to the same S3 bucket that triggers it." Three anomaly types this catches beautifully: NAT Gateway fan-out: A new service routes all egress through a NAT Gateway. Data processing charges creep up invisibly under "EC2-Other." Lambda runaway invocations: A recursive trigger or a bad retry config turns a $5/month function into a $2,000/month function overnight.