GPT-6.1 Sol is One Sentence Away From Collaborating: Other Models Need More Help

TL;DR We studied one ingredient of unexpected AI collaboration: whether agents organize useful teamwork with little prompting. We tested seven models in groups of three on a research task where sharing findings could help each agent answer more questions. GPT-6.1 Sol acted on a nudge. A single line saying agents had been “trained to collaborate” elicited useful collaboration in 9 of 10 runs. Without it, that fell to 0 of 10. No other model collaborated consistently with (or without) this cue. Permission to collaborate unlocked Opus-5.5. When told to work together and how to communicate, GPT-6.1 and Claude Opus 5.5 divided the research and nearly doubled their performance relative to solo runs. The other models talked to each other but did not successfully execute a strategy, and were unable to improve their scores meaningfully. Supplying the strategy helped open weights models and GPT-5.6 Sol. Explicit instructions to divide the questions substantially improved the remaining models’ performance. We suspect differences in multi-agent training help explain why GPT-6.1 organizes collaboration with just a prompt cue. As multi-agent training becomes more widespread, we expect that futur