MEDAL: A Framework for Benchmarking LLMs as Multilingual Open-Domain Dialogue Evaluators

Fuente: arXiv
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Main Authors: Mendonça, John, Lavie, Alon, Trancoso, Isabel
Format: Preprint
Published: 2025
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author Mendonça, John
Lavie, Alon
Trancoso, Isabel
author_facet Mendonça, John
Lavie, Alon
Trancoso, Isabel
contents Evaluating the quality of open-domain chatbots has become increasingly reliant on LLMs acting as automatic judges. However, existing meta-evaluation benchmarks are static, outdated, and lacking in multilingual coverage, limiting their ability to fully capture subtle weaknesses in evaluation. We introduce MEDAL, an automated multi-agent framework for curating more representative and diverse open-domain dialogue evaluation benchmarks. Our approach leverages several state-of-the-art LLMs to generate user-chatbot multilingual dialogues, conditioned on varied seed contexts. Then, a strong LLM (GPT-4.1) is used for a multidimensional analysis of the performance of the chatbots, uncovering noticeable cross-lingual performance differences. Guided by this large-scale evaluation, we curate a new meta-evaluation multilingual benchmark and human-annotate samples with nuanced quality judgments. This benchmark is then used to assess the ability of several reasoning and non-reasoning LLMs to act as evaluators of open-domain dialogues. Using MEDAL, we uncover that state-of-the-art judges fail to reliably detect nuanced issues such as lack of empathy, commonsense, or relevance.
format Preprint
id arxiv_https___arxiv_org_abs_2505_22777
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MEDAL: A Framework for Benchmarking LLMs as Multilingual Open-Domain Dialogue Evaluators
Mendonça, John
Lavie, Alon
Trancoso, Isabel
Computation and Language
Evaluating the quality of open-domain chatbots has become increasingly reliant on LLMs acting as automatic judges. However, existing meta-evaluation benchmarks are static, outdated, and lacking in multilingual coverage, limiting their ability to fully capture subtle weaknesses in evaluation. We introduce MEDAL, an automated multi-agent framework for curating more representative and diverse open-domain dialogue evaluation benchmarks. Our approach leverages several state-of-the-art LLMs to generate user-chatbot multilingual dialogues, conditioned on varied seed contexts. Then, a strong LLM (GPT-4.1) is used for a multidimensional analysis of the performance of the chatbots, uncovering noticeable cross-lingual performance differences. Guided by this large-scale evaluation, we curate a new meta-evaluation multilingual benchmark and human-annotate samples with nuanced quality judgments. This benchmark is then used to assess the ability of several reasoning and non-reasoning LLMs to act as evaluators of open-domain dialogues. Using MEDAL, we uncover that state-of-the-art judges fail to reliably detect nuanced issues such as lack of empathy, commonsense, or relevance.
title MEDAL: A Framework for Benchmarking LLMs as Multilingual Open-Domain Dialogue Evaluators
topic Computation and Language
url https://arxiv.org/abs/2505.22777