Free capacity lies to you the moment you budget only the successful call. An agent that retries, backs off, and re-enters a queue is not getting a mulligan. It is buying a second invoice and a second ticket at the deli counter, and the first sandwich still never showed up.
You already know the happy-path math. One prompt, some completion tokens, a latency you can live with. That spreadsheet is comforting. It is also incomplete. The path that actually burns your afternoon is the one where the model times out, the tool call 500s, or the free endpoint parks you behind a crowd you cannot see.
A retry is capacity. Treat it like capacity or it will treat your calendar like a suggestion.
The bill you did not itemize
Picture a checkout line that resets you to the back every time the cashier drops a bag. You did not steal extra groceries. You still spent extra time. If the store also charges per scan attempt, you spent extra money too. LLM endpoints behave like that store when retries are unbounded and queues are shared.
