ResearchResearch paperReinforcement Learning1 source · Oct 19, 2026

ToolOPD: Credit-Aware On-Policy Distillation for Tool-Use Agents

On-policy distillation (OPD) enhances the capabilities of small language agents by providing dense, token-level supervision from a teacher model on student-generated trajectories.

Key points

  • However, standard OPD implicitly assumes that credit is uniformly distributed across long-horizon trajectories, assigning the same strength of teacher supervision to different actions.
  • Through credit-distribution analysis and outcome-reversal counterfactual experiments, we find that trajectory credit is concentrated on a small number of critical actions.
  • To address these challenges, we propose ToolOPD, an outcome-aware on-policy distillation framework designed for long-horizon tool use.
  • Extensive experiments across multiple long-horizon tool interaction benchmarks demonstrate that ToolOPD significantly outperforms existing reinforcement learning and self-distillation baselines.

Sources (1)

  • [1]ToolOPD: Credit-Aware On-Policy Distillation for Tool-Use Agents
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 19, 02:41 AM
    On-policy distillation (OPD) enhances the capabilities of small language agents by providing dense, token-level supervision from a teacher model on student-generated trajectories.
    However, standard OPD implicitly assumes that credit is uniformly distributed across long-horizon trajectories, assigning the same strength of teacher supervision to different actions.

Extractive summary: sentences quoted from the sources.

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  4. Oct 18, 2026Beyond the Teacher: Understanding and Preserving Distillation Overshoot in Agentic On-Policy Distillation
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