AI Agent Context Window Cost: The Compounding Math Your Architecture Is Hiding

The math isn't complicated. It's just that nobody runs it until they get the bill. An AI agent handling a 10-turn workflow — reading files, calling tools, revising output — doesn't cost 10x a single query. Because transformer inference processes the entire context on every call, cost compounds with each additional turn. The tenth turn carries everything that preceded it: the original file reads, every tool call and its return payload, every intermediate plan and revision. A team that models agen