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Large Language Modelsr/MachineLearningPublished: Jul 15, 2026, 01:00 JST2 min read

New benchmark tests LLM agents' ability to coordinate — most struggle at ~6% performance

Key takeaway

  • 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.

3 Key Points

  1. What happened

    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.

  2. 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.

  3. 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.

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Context & Analysis

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.

FAQ

What do the agents have to do in this benchmark?
Agents must work together to explore, communicate, trade resources, craft tools, build structures, and fight mobs in long-horizon, open-ended worlds.
How did zero-shot Gemini 3.1 Pro perform compared to trained multi-agent systems?
On the hardest setting, zero-shot Gemini 3.1 Pro performed comparably to the best MARL (multi-agent reinforcement learning) agent trained for 1 billion environment steps.
What was the key finding about coordination?
Coordination was identified as a distinct bottleneck beyond long-horizon task competence, with communication having the largest effect in the researchers' ablation tests.
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