The language model call is predictable. You know the token count. You can estimate the cost. The surprise comes from everything the agent calls after the model responds. A single agent action can trigger an external API, a database write, a notification, a webhook, and a storage operation. Each one has its own cost curve. Some charge per-call, some per-record, some per-gigabyte. When an agent loops or retries, every step multiplies. Why Do AI Agent Bills Surprise People? Most tea...