Opus 4.6

UC Berkeley and partner labs released a large-scale model routing study spanning 452 candidate models and policies across 25 benchmarks, totaling 374,401 scored runs. Routers deliver their value mainly by shifting work to cheaper models, averaging 8.82x more quality per unit cost with under 0.5 points lost; on coding tasks routing reached 25.5x the cost efficiency of always calling Opus 4.6 at a 0.44-point loss. Yet learned routers gained only 0.3 points over the best single model, far below the 5.4-point theoretical ceiling.