# ModelJudgePrompt A configuration for how a model evaluator constructs its prompt. ``` struct ModelJudgePrompt where Input : ModelSampleProtocol ``` ## Overview ```swift let prompt = ModelJudgePrompt>( instructions: "You are a domain expert evaluating product reviews." ) ``` `ModelJudgePrompt` bundles the instructions, response presentation, and reference-data injection into a single composable value. Use it with [`ModelJudgeEvaluator`](/documentation/Evaluations/ModelJudgeEvaluator) to customize how the model judge sees the evaluation. ## Topics ### Creating a prompt configuration [`init(instructions:evaluationTarget:reference:)`](/documentation/Evaluations/ModelJudgePrompt/init(instructions:evaluationTarget:reference:)) Creates a model prompt configuration. [`defaultInstructions`](/documentation/Evaluations/ModelJudgePrompt/defaultInstructions) The default system instructions used when no custom instructions are provided. ### Customizing judge input [`instructions`](/documentation/Evaluations/ModelJudgePrompt/instructions) The system instructions for the model judge. [`evaluationTarget`](/documentation/Evaluations/ModelJudgePrompt/evaluationTarget) An optional closure that converts the model’s response to a string for the model prompt. [`reference`](/documentation/Evaluations/ModelJudgePrompt/reference) An optional closure that provides labeled reference data to include in the model prompt. ## Relationships ### Conforms To [`Sendable`](/documentation/Swift/Sendable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)