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The paper introduces Meta-Sel, a supervised meta-learning approach for efficient demonstration selection in in-context learning, which addresses the challenge of selecting optimal few-shot examples under a limited prompt budget. Meta-Sel learns a scoring function based on TF-IDF cosine similarity and length-compatibility ratio between candidate demonstrations and queries, trained on a meta-dataset constructed from training data using class agreement as supervision. Empirical evaluation across four intent datasets and five LLMs demonstrates that Meta-Sel achieves competitive accuracy and selection-time overhead compared to 12 other demonstration selection methods, especially benefiting smaller models.
Forget complex LLM calls or fine-tuning: Meta-Sel distills demonstration selection into a fast, interpretable logistic regression, rivaling more expensive methods.
Demonstration selection is a practical bottleneck in in-context learning (ICL): under a tight prompt budget, accuracy can change substantially depending on which few-shot examples are included, yet selection must remain cheap enough to run per query over large candidate pools. We propose Meta-Sel, a lightweight supervised meta-learning approach for intent classification that learns a fast, interpretable scoring function for (candidate, query) pairs from labeled training data. Meta-Sel constructs a meta-dataset by sampling pairs from the training split and using class agreement as supervision, then trains a calibrated logistic regressor on two inexpensive meta-features: TF--IDF cosine similarity and a length-compatibility ratio. At inference time, the selector performs a single vectorized scoring pass over the full candidate pool and returns the top-k demonstrations, requiring no model fine-tuning, no online exploration, and no additional LLM calls. This yields deterministic rankings and makes the selection mechanism straightforward to audit via interpretable feature weights. Beyond proposing Meta-Sel, we provide a broad empirical study of demonstration selection, benchmarking 12 methods -- spanning prompt engineering baselines, heuristic selection, reinforcement learning, and influence-based approaches -- across four intent datasets and five open-source LLMs. Across this benchmark, Meta-Sel consistently ranks among the top-performing methods, is particularly effective for smaller models where selection quality can partially compensate for limited model capacity, and maintains competitive selection-time overhead.