FML-bench: A Controlled Study of AI Research Agent Strategies from the Perspective of Search Dynamics

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Main Authors: Zou, Qiran, Lam, Hou Hei, Zhao, Wenhao, Chen, Tingting, Tang, Yiming, Yu, Samson, Zhu, Yingtao, Anumasa, Srinivas, Zhang, Zufeng, Zhang, Tianyi, Liu, Chang, Jiang, Zhengyao, Goyal, Anirudh, Liu, Dianbo
Format: Preprint
Published: 2026
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author Zou, Qiran
Lam, Hou Hei
Zhao, Wenhao
Chen, Tingting
Tang, Yiming
Yu, Samson
Zhu, Yingtao
Anumasa, Srinivas
Zhang, Zufeng
Zhang, Tianyi
Liu, Chang
Jiang, Zhengyao
Goyal, Anirudh
Liu, Dianbo
author_facet Zou, Qiran
Lam, Hou Hei
Zhao, Wenhao
Chen, Tingting
Tang, Yiming
Yu, Samson
Zhu, Yingtao
Anumasa, Srinivas
Zhang, Zufeng
Zhang, Tianyi
Liu, Chang
Jiang, Zhengyao
Goyal, Anirudh
Liu, Dianbo
contents AI research agents accelerate ML research by automating hypothesis generation, experimentation, and empirical refinement. Existing agent strategies range from greedy hill-climbing to tree search and evolutionary optimization, yet which strategy choices drive performance remains unclear. Answering this question requires a benchmark that separates agent strategy (e.g., search topology) from execution infrastructure (e.g., code editor), so that performance differences are attributable to strategy rather than infrastructure, and that provides process-level metrics beyond final scores to analyze exploration behaviors. Existing benchmarks offer limited support. We propose FML-Bench, a benchmark of 18 fundamental ML research tasks across 10 domains that separates agent strategy from execution infrastructure and defines 12 process-level behavioral metrics. Evaluating six representative agents, we find that: (1) strategy complexity alone does not guarantee strong performance: a simple greedy hill-climber nearly matches the best-performing tree-search agent, both well above the remaining agents; (2) our analysis suggests this pattern relates to improvement opportunity structure: greedy search tends to be more effective when opportunities are dense, while tree-search and evolutionary strategies tend to be more effective when opportunities are sparse; an adaptive agent built on this insight switches to broader exploration upon detecting improvement stagnation and outperforms the other six agents, lending initial support to this observation; and (3) process-level analysis reveals that early convergence and directionally focused exploration are significantly associated with final performance, while solution diversity and compute cost are not. Our benchmark is available at: https://github.com/qrzou/FML-bench.
format Preprint
id arxiv_https___arxiv_org_abs_2605_17373
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle FML-bench: A Controlled Study of AI Research Agent Strategies from the Perspective of Search Dynamics
Zou, Qiran
Lam, Hou Hei
Zhao, Wenhao
Chen, Tingting
Tang, Yiming
Yu, Samson
Zhu, Yingtao
Anumasa, Srinivas
Zhang, Zufeng
Zhang, Tianyi
Liu, Chang
Jiang, Zhengyao
Goyal, Anirudh
Liu, Dianbo
Machine Learning
Artificial Intelligence
AI research agents accelerate ML research by automating hypothesis generation, experimentation, and empirical refinement. Existing agent strategies range from greedy hill-climbing to tree search and evolutionary optimization, yet which strategy choices drive performance remains unclear. Answering this question requires a benchmark that separates agent strategy (e.g., search topology) from execution infrastructure (e.g., code editor), so that performance differences are attributable to strategy rather than infrastructure, and that provides process-level metrics beyond final scores to analyze exploration behaviors. Existing benchmarks offer limited support. We propose FML-Bench, a benchmark of 18 fundamental ML research tasks across 10 domains that separates agent strategy from execution infrastructure and defines 12 process-level behavioral metrics. Evaluating six representative agents, we find that: (1) strategy complexity alone does not guarantee strong performance: a simple greedy hill-climber nearly matches the best-performing tree-search agent, both well above the remaining agents; (2) our analysis suggests this pattern relates to improvement opportunity structure: greedy search tends to be more effective when opportunities are dense, while tree-search and evolutionary strategies tend to be more effective when opportunities are sparse; an adaptive agent built on this insight switches to broader exploration upon detecting improvement stagnation and outperforms the other six agents, lending initial support to this observation; and (3) process-level analysis reveals that early convergence and directionally focused exploration are significantly associated with final performance, while solution diversity and compute cost are not. Our benchmark is available at: https://github.com/qrzou/FML-bench.
title FML-bench: A Controlled Study of AI Research Agent Strategies from the Perspective of Search Dynamics
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2605.17373