SIGNALAI·Jun 12, 2026, 4:00 AMSignal75Medium term

Keep Policy Gradient in Charge: Sibling-Guided Credit Distillation for Long-Horizon Tool-Use Agents

Source: arXiv cs.CL

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Keep Policy Gradient in Charge: Sibling-Guided Credit Distillation for Long-Horizon Tool-Use Agents

arXiv:2606.12634v1 Announce Type: cross Abstract: Long-horizon tool-use reinforcement learning can learn from outcome verification, but its trajectory-level advantage is broadcast across many reasoning, API, and answer tokens. Self-distillation promises a denser signal by reusing a policy's own rollouts or a privileged teacher. We show, however, that direct token-level self-distillation can silently destroy tool use: it rehearses teacher behavior without knowing which actions the verifier rewards, so useful skills and harmful shortcuts are amplified together. We introduce Sibling-Guided Credit

Why this matters
Why now

This research addresses a critical challenge in developing robust long-horizon AI agents, which is paramount for practical applications as AI capabilities advance.

Why it’s important

Improving credit assignment in long-horizon tasks is essential for the reliable and scalable development of autonomous AI agents, impacting their deployment across various industries.

What changes

The proposed 'Sibling-Guided Credit Distillation' method offers a more stable and effective way to train tool-use agents, potentially accelerating their reliability and widespread adoption.

Winners
  • · AI software developers
  • · Automation industries
  • · AI agent providers
Losers
  • · Companies relying on brittle AI systems
Second-order effects
Direct

More capable and trustworthy autonomous AI agents become available for complex tasks.

Second

Increased adoption of AI agents leads to automation of more sophisticated workflows.

Third

The definition of white-collar work shifts significantly as agents take on increasingly complex, multi-step Reasoning tasks, altering labor markets.

Editorial confidence: 90 / 100 · Structural impact: 60 / 100
Original report

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Read at arXiv cs.CL
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