Tool-R0: Self-Evolving LLM Agents for Tool-Learning from Zero Data

Emre Can Acikgoz, Cheng Qian, Jonas Hübotter, Heng Ji, Dilek Hakkani-Tür, Gokhan Tur


Abstract
Large language models (LLMs) are becoming the foundation for autonomous agents that can use tools to solve complex tasks. Reinforcement learning (RL) has emerged as a common approach for injecting such agentic capabilities, but typically under tightly controlled training setups. It often depends on carefully curated task–solution pairs and substantial human supervision, which creates a fundamental obstacle to open-ended self-evolution. In this paper, we propose Tool-R0 for training general purpose tool-calling agents from scratch with self-play RL, under a zero-data assumption. Initialized from the same base LLM, Tool-R0 co-evolves a Generator and a Solver with complementary rewards: one proposes targeted challenging tasks at the other’s competence frontier and the other learns to solve them with real-world tool calls. This creates a self-evolving cycle that requires no pre-existing datasets. Evaluation on five tool-use benchmarks show that Tool-R0 yields 92.5% relative improvement over the base model and surpasses fully supervised tool-calling baselines under the same setting. Our work further provides empirical insights into self-play LLM agents by analyzing co-evolution, curriculum dynamics, and scaling behavior.
Anthology ID:
2026.findings-emnlp.1407
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
29989–30017
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1407/
DOI:
Bibkey:
Cite (ACL):
Emre Can Acikgoz, Cheng Qian, Jonas Hübotter, Heng Ji, Dilek Hakkani-Tür, and Gokhan Tur. 2026. Tool-R0: Self-Evolving LLM Agents for Tool-Learning from Zero Data. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 29989–30017, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Tool-R0: Self-Evolving LLM Agents for Tool-Learning from Zero Data (Acikgoz et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1407.pdf