Anthropic finds single AI agent outperforms multi-agent setups as models handle complexity alone

Anthropic's testing shows a single agent with on-demand context often outperforms multi-agent setups in quality, cost, and latency. Newer models including Opus 4.5, Opus 5.5 and Fable 5.1 can manage complex plans directly in a single loop. In one comparison, the single-agent architecture ran about twice as fast as the multi-agent setup. The company recommends evaluating consolidation of sub-agents, noting that a single primary agent frequently beats monolithic prompt designs and sub-agent setups on quality.