FahMai-TeleBench: A Thai Grounded Tool-Use Benchmark for the Deployable Model Tier

Nutchanon Yongsatianchot, Piyalitt Ittichaiwong, Jitkapat Sawatphol, Tichanat Ruangsiri


Abstract
Multilingual agentic benchmarks remain rare, especially for under-resourced languages such as Thai, where nicknames, unspaced script, and fused honorifics change how an agent must query its tools. We present FahMai-TeleBench, a bilingual (Thai/English) benchmark for grounded tool use. A model answers employee-directory questions over a synthetic company directory by issuing tool calls, or refuses when the answer is absent. All 626 items are synthetic but modeled on a real Thai enterprise-directory deployment, and they are graded deterministically without an LLM judge. Our central design choice is to treat tool availability as an experimental variable: each item runs under four tool configurations (grep, structured search, both, and a Python REPL), so the benchmark measures not just whether a model answers but how it uses tools. The task is near-solved at the frontier (GPT-5.4 97–99%), yet sharply discriminating for the Thai-capable models an organization would host itself (Typhoon-2.5 58–74%, Typhoon-S-8B 25–37%). The Thai penalty is model-specific, and Typhoon-2.5 answers 90% of items correctly once the relevant records are placed in its context, so its failures are failures of tool use. The tool axis also exposes differences at the frontier: GPT-5.5 drops to 73% with a wide-schema structured search tool while scoring 97–98% with grep and the REPL.
Anthology ID:
2026.aacl-short.15
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 2: Short Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
185–196
Language:
URL:
https://aclanthology.org/2026.aacl-short.15/
DOI:
Bibkey:
Cite (ACL):
Nutchanon Yongsatianchot, Piyalitt Ittichaiwong, Jitkapat Sawatphol, and Tichanat Ruangsiri. 2026. FahMai-TeleBench: A Thai Grounded Tool-Use Benchmark for the Deployable Model Tier. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 2: Short Papers), pages 185–196, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
FahMai-TeleBench: A Thai Grounded Tool-Use Benchmark for the Deployable Model Tier (Yongsatianchot et al., AACL-IJCNLP 2026)
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https://aclanthology.org/2026.aacl-short.15.pdf