opus 5.5 took the top spot on epoch's capabilities index.
a while ago, astra was sitting on top.
now a model at less than half the price is sitting right next to it.
and sonnet 5.5, anthropic's mid tier model is already matching fable 5.1
Claude Opus 5.5 has taken the top spot on the Epoch Capabilities Index (ECI) with a score of 167, narrowly ahead of GPT-6 Astra.
Claude Sonnet 5.5 has roughly matched Claude Fable 5.1 (165).