What they did
The authors designed Alem, a procedurally generated survival world incorporating exploration, crafting, trading, and combat, along with coordination tasks requiring soft specialization, communication, and controllable difficulty. They evaluated 13 modern LLMs zero-shot in homogeneous teams of agents, using trained MARL (multi-agent reinforcement learning) agents as reference points. The environment is built in JAX to support efficient parallel simulation.
Key findings
- All LLM agents averaged only ~6% normalized return, far below the trained MARL baselines.
- In the hardest coordination setting, zero-shot Gemini-3.1-Pro-High approached the performance of MARL agents trained for one billion steps.
- GPT-5.4-High achieved strong base-task reward but much lower coordination reward, indicating individual competence does not imply coordination competence.
- Ablations show that communication is the largest contributor to coordination performance, while memory and reasoning help primarily when maintaining multi-step plans.
Why it matters
This work isolates coordination as a distinct capability bottleneck for frontier LLM agents, separate from single-agent skills. By providing a controlled, open-ended testbed, Alem enables systematic measurement and improvement of multi-agent coordination, which is critical for deploying LLMs in real-world collaborative settings.
Caveats
The evaluation is limited to homogeneous teams (all agents using the same LLM) and zero-shot prompting; fine-tuned or heterogeneous teams might yield different results. The base MARL agents were trained for up to one billion steps, which may not be directly comparable to zero-shot LLM performance. The benchmark's complexity may also conflate multiple coordination challenges.