CCTU: A Benchmark for Tool Use under Complex Constraints

Fuente: arXiv
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Main Authors: Ye, Junjie, Zhang, Guoqiang, Fu, Wenjie, Gui, Tao, Zhang, Qi, Huang, Xuanjing
Format: Preprint
Published: 2026
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author Ye, Junjie
Zhang, Guoqiang
Fu, Wenjie
Gui, Tao
Zhang, Qi
Huang, Xuanjing
author_facet Ye, Junjie
Zhang, Guoqiang
Fu, Wenjie
Gui, Tao
Zhang, Qi
Huang, Xuanjing
contents Solving problems through tool use under explicit constraints constitutes a highly challenging yet unavoidable scenario for large language models (LLMs), requiring capabilities such as function calling, instruction following, and self-refinement. However, progress has been hindered by the absence of dedicated evaluations. To address this, we introduce CCTU, a benchmark for evaluating LLM tool use under complex constraints. CCTU is grounded in a taxonomy of 12 constraint categories spanning four dimensions (i.e., resource, behavior, toolset, and response). The benchmark comprises 200 carefully curated and challenging test cases across diverse tool-use scenarios, each involving an average of seven constraint types and an average prompt length exceeding 4,700 tokens. To enable reliable evaluation, we develop an executable constraint validation module that performs step-level validation and enforces compliance during multi-turn interactions between models and their environments. We evaluate nine state-of-the-art LLMs in both thinking and non-thinking modes. Results indicate that when strict adherence to all constraints is required, no model achieves a task completion rate above 20%. Further analysis reveals that models violate constraints in over 50% of cases, particularly in the resource and response dimensions. Moreover, LLMs demonstrate limited capacity for self-refinement even after receiving detailed feedback on constraint violations, highlighting a critical bottleneck in the development of robust tool-use agents. To facilitate future research, we release the data and code.
format Preprint
id arxiv_https___arxiv_org_abs_2603_15309
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle CCTU: A Benchmark for Tool Use under Complex Constraints
Ye, Junjie
Zhang, Guoqiang
Fu, Wenjie
Gui, Tao
Zhang, Qi
Huang, Xuanjing
Computation and Language
Artificial Intelligence
Solving problems through tool use under explicit constraints constitutes a highly challenging yet unavoidable scenario for large language models (LLMs), requiring capabilities such as function calling, instruction following, and self-refinement. However, progress has been hindered by the absence of dedicated evaluations. To address this, we introduce CCTU, a benchmark for evaluating LLM tool use under complex constraints. CCTU is grounded in a taxonomy of 12 constraint categories spanning four dimensions (i.e., resource, behavior, toolset, and response). The benchmark comprises 200 carefully curated and challenging test cases across diverse tool-use scenarios, each involving an average of seven constraint types and an average prompt length exceeding 4,700 tokens. To enable reliable evaluation, we develop an executable constraint validation module that performs step-level validation and enforces compliance during multi-turn interactions between models and their environments. We evaluate nine state-of-the-art LLMs in both thinking and non-thinking modes. Results indicate that when strict adherence to all constraints is required, no model achieves a task completion rate above 20%. Further analysis reveals that models violate constraints in over 50% of cases, particularly in the resource and response dimensions. Moreover, LLMs demonstrate limited capacity for self-refinement even after receiving detailed feedback on constraint violations, highlighting a critical bottleneck in the development of robust tool-use agents. To facilitate future research, we release the data and code.
title CCTU: A Benchmark for Tool Use under Complex Constraints
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2603.15309