Agent Collaboration

A single Claude Opus 5.5 agent allowed fifteen tool calls answers a medium-sized research question for about 59 cents in three and a half minutes. A lead agent that splits the same question among four Claude Sonnet 5 subagents answers it for $1.14 in just over four minutes, and reads 2.7 times as many sources on the way. Both figures come from the cost model built below, at list prices as of September 2026, and together they pose the first decision in multi-agent design: is the extra reading worth 55 cents a question, or worth nothing at all?