OpenAI: Two API Settings Tripled GPT-5.6 Sol's ARC-AGI-3 Score

OpenAI reports that enabling retained reasoning and compaction in its Responses API raised GPT-5.6 Sol's ARC-AGI-3 score from 13.3% to 38.3%, while reducing output tokens by about six times. The result highlights that benchmark scores depend on the evaluation harness, not just the model. For developers, this underscores the importance of API configuration in agent performance and token efficiency.