CAPO: Cost-Aware Prompt Optimization

Fuente: arXiv
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Hauptverfasser: Zehle, Tom, Schlager, Moritz, Heiß, Timo, Feurer, Matthias
Format: Preprint
Veröffentlicht: 2025
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author Zehle, Tom
Schlager, Moritz
Heiß, Timo
Feurer, Matthias
author_facet Zehle, Tom
Schlager, Moritz
Heiß, Timo
Feurer, Matthias
contents Large language models (LLMs) have revolutionized natural language processing by solving a wide range of tasks simply guided by a prompt. Yet their performance is highly sensitive to prompt formulation. While automatic prompt optimization addresses this challenge by finding optimal prompts, current methods require a substantial number of LLM calls and input tokens, making prompt optimization expensive. We introduce CAPO (Cost-Aware Prompt Optimization), an algorithm that enhances prompt optimization efficiency by integrating AutoML techniques. CAPO is an evolutionary approach with LLMs as operators, incorporating racing to save evaluations and multi-objective optimization to balance performance with prompt length. It jointly optimizes instructions and few-shot examples while leveraging task descriptions for improved robustness. Our extensive experiments across diverse datasets and LLMs demonstrate that CAPO outperforms state-of-the-art discrete prompt optimization methods in 11/15 cases with improvements up to 21%p in accuracy. Our algorithm achieves better performances already with smaller budgets, saves evaluations through racing, and decreases average prompt length via a length penalty, making it both cost-efficient and cost-aware. Even without few-shot examples, CAPO outperforms its competitors and generally remains robust to initial prompts. CAPO represents an important step toward making prompt optimization more powerful and accessible by improving cost-efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2504_16005
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle CAPO: Cost-Aware Prompt Optimization
Zehle, Tom
Schlager, Moritz
Heiß, Timo
Feurer, Matthias
Computation and Language
Artificial Intelligence
Neural and Evolutionary Computing
Machine Learning
Large language models (LLMs) have revolutionized natural language processing by solving a wide range of tasks simply guided by a prompt. Yet their performance is highly sensitive to prompt formulation. While automatic prompt optimization addresses this challenge by finding optimal prompts, current methods require a substantial number of LLM calls and input tokens, making prompt optimization expensive. We introduce CAPO (Cost-Aware Prompt Optimization), an algorithm that enhances prompt optimization efficiency by integrating AutoML techniques. CAPO is an evolutionary approach with LLMs as operators, incorporating racing to save evaluations and multi-objective optimization to balance performance with prompt length. It jointly optimizes instructions and few-shot examples while leveraging task descriptions for improved robustness. Our extensive experiments across diverse datasets and LLMs demonstrate that CAPO outperforms state-of-the-art discrete prompt optimization methods in 11/15 cases with improvements up to 21%p in accuracy. Our algorithm achieves better performances already with smaller budgets, saves evaluations through racing, and decreases average prompt length via a length penalty, making it both cost-efficient and cost-aware. Even without few-shot examples, CAPO outperforms its competitors and generally remains robust to initial prompts. CAPO represents an important step toward making prompt optimization more powerful and accessible by improving cost-efficiency.
title CAPO: Cost-Aware Prompt Optimization
topic Computation and Language
Artificial Intelligence
Neural and Evolutionary Computing
Machine Learning
url https://arxiv.org/abs/2504.16005