Researchers have published a new benchmark that evaluates how well 13 modern large language models can coordinate as agents in open-ended, long-horizon worlds. Most agents performed poorly, averaging only ~6% normalised return, revealing that coordination is a distinct challenge beyond individual task competence. Notably, zero-shot Gemini 3.1 Pro performed as well as the best multi-agent reinforcement learning agent trained for 1 billion environment steps on the hardest setting, and ablation tests showed that communication has the largest effect on coordination success.
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Researchers evaluated 13 modern LLMs in a new benchmark requiring agents to coordinate in open-ended worlds—exploring, communicating, trading resources, crafting tools, building structures, and fighting mobs. Most agents averaged only ~6% normalised return, though zero-shot Gemini 3.1 Pro matched the best multi-agent reinforcement learning (MARL) agent trained for 1 billion environment steps on the hardest setting.
Why it matters
The benchmark reveals that coordination is a distinct bottleneck separate from long-horizon task competence. Communication emerged as the single largest factor in ablation tests, suggesting that how well agents exchange information—not just individual task ability—determines team success. This finding matters for understanding what language models still need to master before reliably working together in complex environments.
What to watch
The full paper, project page with leaderboard, code, and interactive traces are publicly available, allowing the research community to test their own agents and track progress on this coordination challenge.
A new research benchmark tests whether large language model agents can coordinate effectively in complex, open-ended environments. The researchers evaluated 13 modern LLMs on tasks that require agents to explore worlds together, communicate with each other, trade resources, craft tools, build structures, and fight enemies.
The results reveal a stark performance gap. Most agents achieved only ~6% normalised return—a sign that coordination at scale remains difficult for current models. However, the benchmark did uncover one standout: zero-shot Gemini 3.1 Pro (run without any special training or prompting) matched the performance of the best multi-agent reinforcement learning agent that had been trained for 1 billion environment steps when tested on the hardest difficulty setting. This suggests that at least one foundation model has learned some coordination behaviors implicitly from its training data.
Beyond individual results, the research team identified coordination as a distinct problem separate from long-horizon task competence—meaning that even agents good at multi-step reasoning sometimes fail to coordinate well. In ablation tests (where they systematically disabled different capabilities), communication had the largest measured effect on team success, indicating that how well agents exchange information and align on goals is the primary bottleneck.
The full paper, project page with a public leaderboard, code, and interactive traces of agent behavior have all been released, inviting the broader research community to benchmark their own models and work toward improving LLM coordination.
The benchmark addresses a practical gap in AI evaluation: while individual LLMs have demonstrated impressive capabilities on long-horizon reasoning tasks, far less is known about their ability to work together effectively in shared environments. By designing scenarios that require exploration, resource trading, tool crafting, and collective problem-solving, the researchers created a setting where agent ability must be paired with team coordination.
The striking performance gap—most agents at ~6% normalised return—suggests that modern LLMs out of the box lack robust multi-agent coordination strategies. The fact that zero-shot Gemini 3.1 Pro matched MARL agents trained for 1 billion environment steps on the hardest setting indicates that some foundation models have learned coordination behaviors, but the majority have not. The ablation finding that communication is the largest lever is concrete and actionable: it points toward communication protocols and information exchange as the most fruitful area for improving team performance, rather than raw individual capability.
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