Reducing Cost of LLM Agents with Trajectory Reduction

Fuente: arXiv
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Main Authors: Xiao, Yuan-An, Gao, Pengfei, Peng, Chao, Xiong, Yingfei
Format: Preprint
Published: 2025
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author Xiao, Yuan-An
Gao, Pengfei
Peng, Chao
Xiong, Yingfei
author_facet Xiao, Yuan-An
Gao, Pengfei
Peng, Chao
Xiong, Yingfei
contents Multi-turn agent systems based on Large Language Models (LLMs) have become increasingly popular for software engineering tasks. While LLM agents demonstrate promising effectiveness, the high computational cost of input tokens due to ever-growing trajectories remains a significant efficiency concern. Efficiency has been largely overlooked in existing studies and agent products, and this paper addresses this gap by introducing an inference-time trajectory reduction approach that reduces computational costs. By analyzing existing agent trajectories, we demonstrate that useless, redundant, and expired information is widespread across trajectories. Such waste can be identified and reduced without compromising the agent's performance. We propose a simple yet effective trajectory reduction approach, AgentDiet, which automatically removes such waste during agent execution. We implement AgentDiet on a top-performing coding agent, and our evaluation on two LLMs and two benchmarks shows that AgentDiet can reduce input tokens by 39.9%-59.7% and the total computational cost by 21.1%-35.9%, while maintaining the same agent performance. These results indicate that inference-time trajectory reduction is a promising direction for agent systems.
format Preprint
id arxiv_https___arxiv_org_abs_2509_23586
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Reducing Cost of LLM Agents with Trajectory Reduction
Xiao, Yuan-An
Gao, Pengfei
Peng, Chao
Xiong, Yingfei
Software Engineering
Artificial Intelligence
Multi-turn agent systems based on Large Language Models (LLMs) have become increasingly popular for software engineering tasks. While LLM agents demonstrate promising effectiveness, the high computational cost of input tokens due to ever-growing trajectories remains a significant efficiency concern. Efficiency has been largely overlooked in existing studies and agent products, and this paper addresses this gap by introducing an inference-time trajectory reduction approach that reduces computational costs. By analyzing existing agent trajectories, we demonstrate that useless, redundant, and expired information is widespread across trajectories. Such waste can be identified and reduced without compromising the agent's performance. We propose a simple yet effective trajectory reduction approach, AgentDiet, which automatically removes such waste during agent execution. We implement AgentDiet on a top-performing coding agent, and our evaluation on two LLMs and two benchmarks shows that AgentDiet can reduce input tokens by 39.9%-59.7% and the total computational cost by 21.1%-35.9%, while maintaining the same agent performance. These results indicate that inference-time trajectory reduction is a promising direction for agent systems.
title Reducing Cost of LLM Agents with Trajectory Reduction
topic Software Engineering
Artificial Intelligence
url https://arxiv.org/abs/2509.23586