Why agent runs cost what they cost
Why is running an AI agent so much more expensive than a single API call?
An agent doesn’t answer once — it loops: perceive, plan, act, verify, reflect. Each step is a separate API call, and every step re-sends the accumulated context: the system prompt, the tools, and the full history so far. So one task is often 5 to 30 calls whose input grows on every step. With the defaults above, the last step alone carries several times the tokens of the first — which is why agent costs scale far faster than a one-shot chat completion.
How do I reduce AI agent costs?
The biggest lever is routing: send the routine steps — tool calls, formatting, simple decisions — to a cheap, fast model, and reserve a frontier model only for the genuinely hard reasoning. Caching the static prompt prefix and trimming history help too. Routing alone usually cuts agent spend 40–80% with no quality loss on the steps that never needed the big model in the first place.
What is LLM model routing?
Routing automatically picks the cheapest model that still clears the quality bar for each individual step, instead of sending everything to one expensive model. Because most steps in an agent loop are routine, routing them to a cheaper model captures most of the savings while keeping frontier quality exactly where it matters. The slider above lets you see the trade-off for your own loop.
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