Does telling an LLM to "be concise" actually save you money? We measured it across 9 models. Compressing the output can save you money and keep accuracy, compressing the input prompt does not. [R]

Excerpt

LLMs are too verbose and with a black box model the only things you control are what goes in and how you tell it to write back. Yesterday Claude Code shipped a "concise output style" where Claude keeps things short. We already have a paper out about this! We tested both channels, shortening the input prompt versus telling the model to output answer shorter, on the same questions across five reduction levels, and scored cost, accuracy, and whether the shortened text still matched what the model w