GPT-5.6 Terra is the balanced everyday assistant in the 5.6 family—most of Sol's follow-through at a lower price. Our tests show very strong helpfulness, instruction following, and comprehension, on par with or slightly ahead of GPT-5.5 for practical tasks. Empathy is competent but cooler than Claude. Creative writing is a clear weak spot: the same compressed internal reasoning that makes 5.5+ models token-efficient for agents produces utilitarian, get-it-done prose. A solid default when reliability matters more than voice.