  This paper presents FoFo, a pioneering benchmark for evaluating large
language models' (LLMs) ability to follow complex, domain-specific formats, a
crucial yet underexamined capability for their application as AI agents.
Despite LLMs' advancements, existing benchmarks fail to assess their
format-following proficiency adequately. FoFo fills this gap with a diverse
range of real-world formats and instructions, developed through an AI-Human
collaborative method. Our evaluation across both open-source (e.g., Llama 2,
WizardLM) and closed-source (e.g., GPT-4, PALM2, Gemini) LLMs highlights three
key findings: open-source models significantly lag behind closed-source ones in
format adherence; LLMs' format-following performance is independent of their
content generation quality; and LLMs' format proficiency varies across
different domains. These insights suggest the need for specialized tuning for
format-following skills and highlight FoFo's role in guiding the selection of
domain-specific AI agents. FoFo is released here at
https://github.com/SalesforceAIResearch/FoFo.
