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Main Authors: Lin, Yuxiang, Wang, Zihan, Liu, Mengyang, Shan, Yuxuan, Bai, Longju, Zhang, Junyao, Jin, Xing, Chen, Boshan, Su, Jinyan, Wang, Xingyao, Pei, Jiaxin, Li, Manling
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2606.00198
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author Lin, Yuxiang
Wang, Zihan
Liu, Mengyang
Shan, Yuxuan
Bai, Longju
Zhang, Junyao
Jin, Xing
Chen, Boshan
Su, Jinyan
Wang, Xingyao
Pei, Jiaxin
Li, Manling
author_facet Lin, Yuxiang
Wang, Zihan
Liu, Mengyang
Shan, Yuxuan
Bai, Longju
Zhang, Junyao
Jin, Xing
Chen, Boshan
Su, Jinyan
Wang, Xingyao
Pei, Jiaxin
Li, Manling
contents While agents are increasingly spending more resources, today agent cost is mostly measured only after execution. A Budget-Aware Agent (BAGEN) should treat budget as an active control signal, rather than a passive cost metric. We first systematically define budget estimation as internal budgets (from agent computation) and external budgets (from agent actions). We then formalize budget-awareness as progressive interval estimation: at each step of a plan, an agent should predict an upper and lower bound on remaining budget, and alert when completion is unlikely. Scoring with a rollout-replay protocol, we find consistent failure patterns on four environments and five frontier agents: (1) strong agents do not necessarily have strong budget-awareness, with correlation r=0.35. (2) frontier models are consistently over-optimistic, continue spending on tasks that are unlikely to succeed, instead of alerting the user early. (3) budget-aware signal is actionable and trainable. Early stop saves 28-64% tokens on failed trajectories, and SFT+RL strengthens early stop and alert behavior. (4) precise interval calibration remains challenging, with interval coverage capping at 47% after SFT+RL. Project page: https://ragen-ai.github.io/bagen/
format Preprint
id arxiv_https___arxiv_org_abs_2606_00198
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle BAGEN: Are LLM Agents Budget-Aware?
Lin, Yuxiang
Wang, Zihan
Liu, Mengyang
Shan, Yuxuan
Bai, Longju
Zhang, Junyao
Jin, Xing
Chen, Boshan
Su, Jinyan
Wang, Xingyao
Pei, Jiaxin
Li, Manling
Machine Learning
Artificial Intelligence
Computation and Language
While agents are increasingly spending more resources, today agent cost is mostly measured only after execution. A Budget-Aware Agent (BAGEN) should treat budget as an active control signal, rather than a passive cost metric. We first systematically define budget estimation as internal budgets (from agent computation) and external budgets (from agent actions). We then formalize budget-awareness as progressive interval estimation: at each step of a plan, an agent should predict an upper and lower bound on remaining budget, and alert when completion is unlikely. Scoring with a rollout-replay protocol, we find consistent failure patterns on four environments and five frontier agents: (1) strong agents do not necessarily have strong budget-awareness, with correlation r=0.35. (2) frontier models are consistently over-optimistic, continue spending on tasks that are unlikely to succeed, instead of alerting the user early. (3) budget-aware signal is actionable and trainable. Early stop saves 28-64% tokens on failed trajectories, and SFT+RL strengthens early stop and alert behavior. (4) precise interval calibration remains challenging, with interval coverage capping at 47% after SFT+RL. Project page: https://ragen-ai.github.io/bagen/
title BAGEN: Are LLM Agents Budget-Aware?
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2606.00198