Exa vs Tavily vs Serper vs Brave Search for AI Agents — AN Score Comparison

Search is the most fundamental thing an agent does. Before it writes, plans, acts, or decides - it looks something up. You'd expect this to be a solved problem. It mostly is. But "mostly" is where agents fail. We scored five search APIs on Rhumb's AN Score framework: 20 dimensions covering execution reliability, error quality, auth predictability, and access readiness. The spread is narrower than CRMs or databases - search APIs are simpler primitives - but the differences compound when your agent runs search loops overnight.