# J-tau: A Fully Localized Japanese Benchmark for Tool-Agent-User Interaction

> Source: <https://www.machinebrief.com/news/j-tau-a-fully-localized-japanese-benchmark-for-tool-agent-us-hf4q>
> Published: 2026-10-15 04:00:00+00:00

arXiv:2610.19638v1 Announce Type: new 
Abstract: We present J-tau, the first publicly available Japanese benchmark for evaluating tool-using LLM agents in interactive customer-support scenarios. While tau-bench is widely used to evaluate LLM agents, it is English-centric and cannot evaluate agents in other languages. Existing multilingual extensions offer no public Japanese version and rely primarily on machine translation, leaving locale-specific entities such as addresses and currencies inconsistent with the target region. To enable reliable evaluation in Japanese, we carefully localize tau-bench through machine translation, entity adaptation, and human review. During this process, we also uncover and fix two flaws in the original tau-bench: invalid tasks and a score aggregation error that inflates certain models' results. Experiments show that J-tau yields fewer evaluation errors than a naively machine-translated counterpart and that our fixes resolve both flaws.