Learning Interaction-Centric Capability Representation for LLM Tool Calling

Hanyi Wang, Ruihan Jin, Jinyang Wu, Zhengqi Wen, Jianhua Tao


Abstract
As large language models (LLMs) increasingly serve as the backbone of agentic systems with tool-use capabilities, predicting correctness, latency, and cost for a given tool-calling query is essential for efficient model evaluation, selection, and routing. Existing approaches predominantly adopt a semantics-first perspective, without capturing the complex interaction patterns inherent in tool-calling queries and without jointly accounting for cost and latency. We observe that query-model interaction matrices in tool-calling scenarios exhibit a low-rank structure, indicating that behavioral outcomes are governed by latent factors beyond surface semantics. We leverage this observation to propose a dual-pathway framework that decomposes interaction matrices into low-dimensional latent spaces for multi-objective prediction. The **Capability-First (CF)** pathway discovers latent structure via matrix factorization and then projects natural language queries into latent space. The **Joint Capability-Semantic (JCS)** pathway concurrently optimizes the text encoder and model embeddings, implicitly shaping query embeddings through capability-semantic interactions. Experiments on 75 LLMs demonstrate strong performance in predicting correctness, latency, and cost. Further experiments show that our method enables few-shot unseen-model generalization, parameter-efficient training, and interpretable latent representations.
Anthology ID:
2026.emnlp-main.1904
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
43394–43409
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1904/
DOI:
Bibkey:
Cite (ACL):
Hanyi Wang, Ruihan Jin, Jinyang Wu, Zhengqi Wen, and Jianhua Tao. 2026. Learning Interaction-Centric Capability Representation for LLM Tool Calling. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 43394–43409, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Learning Interaction-Centric Capability Representation for LLM Tool Calling (Wang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1904.pdf