Do Tools Matter, or Just Their Descriptions?

Ananya Tomar, Ayush Nangia


Abstract
Tool-augmented language models are increasingly applied to financial document reasoning, a setting that demands numerical precision over long financial filings. Earlier comparisons either mix up the model with its scaffolding or report tool-use gains without separating code, strategy, and environment. We isolate these factors in a controlled same-model ablation: six configurations share an identical GPT-5 backbone and differ only in the tool surface (callable tools plus their descriptions), with one control that additionally forces sub-model delegation. On DocMath-Eval under oracle context, the fully equipped configuration beats the restricted-tool baseline by +3.6 points (p=0.0028). Where this gain comes from matters more than its size: the system tools that give that configuration its name are used on under 0.2% of samples, and a description-only control, which describes the same tools but never runs them, performs almost identically (within 1 point on every split). The benefit comes from the tool descriptions, not from executing the tools. On long-document splits, the equipped model uses fewer iterations, has answers available earlier when runs are cut short, and varies its tool mix with document length. Comprehension errors dominate the hardest failures: the bottleneck is document comprehension, not the tool interface.
Anthology ID:
2026.finnlp-1.54
Volume:
Proceedings of the 11th Workshop on Financial Technology and Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Jimin Huang, Yongjae Lee, Sophia Ananiadou, Hsin-Hsi Chen, Hiroya Takamura, Chung-Chi Chen
Venues:
FinNLP | WS
SIG:
SIGFinTech
Publisher:
Association for Computational Linguistics
Note:
Pages:
650–666
Language:
URL:
https://aclanthology.org/2026.finnlp-1.54/
DOI:
Bibkey:
Cite (ACL):
Ananya Tomar and Ayush Nangia. 2026. Do Tools Matter, or Just Their Descriptions?. In Proceedings of the 11th Workshop on Financial Technology and Natural Language Processing, pages 650–666, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Do Tools Matter, or Just Their Descriptions? (Tomar & Nangia, FinNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.finnlp-1.54.pdf