Ant International and Westlake University release Trajectory2Gym for tool-use agent training

ant-intl · hf · 2026-10-27

Ant International and Westlake University released Trajectory2Gym, addressing a core problem in tool-use agent training: successful trajectories aren't necessarily useful supervision — they may underrepresent multi-step dependencies or include actions unjustified by information visible at decision time.

The paper identifies two coupled requirements for effective trajectory supervision:

Trajectory2Gym constructs executable interactions around under-supported compositional structures and derives supervision only from grounded decisions in realized executions, using structural-support selection to allocate experience and parent-normalized supervised fine-tuning with semantic interactions as training-weight units. This reframes trajectory generation as deliberate construction of learnable experience rather than collection of successful trajectories. Across five Qwen3 scales, it improves results on Tau1. Code and data are open-sourced.

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