Fine-tuning Small Language Models as Efficient Enterprise Search Relevance Labelers
Yue Kang, Zhuoyi Huang, Benji Schussheim, Diana Licon, Dina Atia, Shixing Cao, Jacob Danovitch, Kunho Kim, Billy Norcilien, Jonah Karpman, Mahmound Sayed, Mike Taylor, Tao Sun, Pavel Metrikov, Vipul Agarwal, Chris Quirk, Ye-Yi Wang, Nick Craswell, Irene Shaffer, Tianwei Chen, Sulaiman Vesal, Soundar Srinivasan
TL;DR
This work addresses scalable relevance labeling in enterprise search by building a synthetic-data pipeline that leverages GPT-4o for positive/negative query generation and labeling, BM25 for hard negatives, and distillation into a compact SLM (Phi-3.5 Mini Instruct). The resulting model achieves parity or superiority to GPT-4o on key metrics like $NDCG$ and $Accuracy$ while delivering dramatically higher throughput (RPM) and lower cost (roughly 19× cheaper in token costs). The approach enables scalable offline evaluation and rapid iteration for enterprise-scale retrieval systems, enabling cost-effective, domain-specific relevance judgments without exposing sensitive user data. Overall, the paper demonstrates that carefully curated synthetic data and multi-task instruction tuning can make small models competitive with frontier LLMs for specialized labeling tasks, with tangible practical impact for industry deployments.
Abstract
In enterprise search, building high-quality datasets at scale remains a central challenge due to the difficulty of acquiring labeled data. To resolve this challenge, we propose an efficient approach to fine-tune small language models (SLMs) for accurate relevance labeling, enabling high-throughput, domain-specific labeling comparable or even better in quality to that of state-of-the-art large language models (LLMs). To overcome the lack of high-quality and accessible datasets in the enterprise domain, our method leverages on synthetic data generation. Specifically, we employ an LLM to synthesize realistic enterprise queries from a seed document, apply BM25 to retrieve hard negatives, and use a teacher LLM to assign relevance scores. The resulting dataset is then distilled into an SLM, producing a compact relevance labeler. We evaluate our approach on a high-quality benchmark consisting of 923 enterprise query-document pairs annotated by trained human annotators, and show that the distilled SLM achieves agreement with human judgments on par with or better than the teacher LLM. Furthermore, our fine-tuned labeler substantially improves throughput, achieving 17 times increase while also being 19 times more cost-effective. This approach enables scalable and cost-effective relevance labeling for enterprise-scale retrieval applications, supporting rapid offline evaluation and iteration in real-world settings.
