On October 1 Ai2 released Olmo-core 3, a framework with a redesigned mixture-of-experts (MoE) training system. Its trillion-scale tests show the system performance of the training stack, not the quality of a newly trained model.
Claude Sonnet 5.5 keeps Sonnet 5’s base input and output rates, but changing the model ID alone can break a Messages API integration. Disabled thinking and forced tool_choice any/tool return HTTP 400; applications must also handle thinking blocks rather than assume the first response block is text.