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AI 智能体评估:Strands Evals 实现生产就绪

·7 分钟阅读·AWS·原始来源
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Strands Evals 架构图,展示了案例、实验和评估器之间为全面 AI 智能体评估而进行的交互。

实验充当测试套件,协调整个评估过程。它将多个案例和一个或多个配置的评估器汇集在一起。在评估运行期间,实验会获取每个案例,将其输入提供给您的 AI 智能体,收集智能体的响应和执行轨迹,然后将这些结果传递给指定的评估器进行评分。这种抽象确保了评估在定义的一组场景中是系统化且可重复的。

最后,评估器是该系统中的“裁判”。它们仔细检查您的智能体产生的结果——其实际输出和操作轨迹——并将其与预期或期望进行比较。与简单的断言检查不同,Strands Evals 的评估器主要基于 LLM。这是一个关键的区别;通过利用语言模型,评估器可以对相关性、有用性、连贯性和忠实性等质量属性做出复杂而细致的判断——这些属性是仅通过字符串比较无法准确评估的。这种灵活而严谨的判断能力对于有效评估用于生产的 AI 智能体至关重要。

任务函数:连接智能体执行与评估

为了将您的 AI 智能体与 Strands Evals 框架集成,需要使用一个称为任务函数的关键组件。这个可调用函数充当桥梁,接收一个 Case 对象,并返回通过您的智能体系统运行该特定案例的结果。此接口高度灵活,支持两种根本不同的评估模式:在线和离线。有关为实际部署准备 AI 智能体的更多见解,请探索 智能化 AI 智能体操作:利益相关者指南第一部分

在线评估涉及在评估运行期间实时调用您的 AI 智能体。任务函数动态创建一个智能体实例,发送案例的输入,捕获智能体的实时响应,并记录其执行轨迹。这种模式在开发阶段非常宝贵,可以提供即时更改反馈,并且对于在部署前需要验证智能体行为的持续集成和交付 (CI/CD) 管道至关重要。它确保在智能体的实际运行状态下评估其性能。

from strands import Agent

def online_task(case):
    agent = Agent(tools=[search_tool, calculator_tool])
    result = agent(case.input)

    return {
        "output": str(result),
        "trajectory": agent.session
    }

相反,离线评估则处理历史数据。任务函数不启动实时智能体,而是从日志、数据库或可观测性系统等来源检索先前记录的交互轨迹。然后,它将这些历史轨迹解析为评估器所需的格式,从而实现评估。这种方法对于评估生产流量、进行历史性能分析或在不产生实时重新运行智能体计算成本的情况下,针对一组一致的真实用户交互比较不同智能体版本非常有效。它特别适用于回顾性分析和大规模数据集评估。

def offline_task(case):
    trace = load_trace_from_database(case.session_id)
    session = session_mapper.map_to_session(trace)

    return {
        "output": extract_final_response(trace),
        "trajectory": session
    }

无论您是测试新实现的智能体还是仔细审查数月的生产数据,Strands Evals 内同样强大的评估器和稳健的报告基础设施都适用。任务函数抽象了数据源,将其无缝适配到评估系统,从而为智能体性能提供一致且全面的洞察。集成这种强大的评估是高级智能体编程工作流的关键,类似于 Xcode 智能体编程中讨论的那些。

使用内置评估器评估智能体质量

随着任务函数有效地将智能体输出传送到评估系统,下一个关键步骤是确定要衡量智能体质量的哪些方面。Strands Evals 旨在提供全面的评估,因此它提供了一套内置评估器。每个评估器都经过专门设计,旨在针对和评估 AI 智能体性能和输出质量的不同维度。

该框架认识到智能体质量是多方面的。仅仅生成文本对智能体来说是不够的;该文本必须有用、相关、连贯,并且忠实于其上下文或源材料。传统指标通常无法捕捉这些主观但关键的属性。这正是前面提到过的基于 LLM 的评估器的力量变得不可或缺的地方。通过利用大语言模型本身充当判断者,Strands Evals 可以执行复杂的定性评估。这些 LLM 可以分析智能体的响应对其用户的总体实用性、其逻辑流程、其对指定事实或指令的遵守情况以及其在对话中保持一致性的能力。这种智能的、细致的判断使开发人员能够超越简单的关键词匹配,真正理解他们的 AI 智能体在实际场景中的有效性和可靠性。

结论:使用 Strands Evals 确保 AI 智能体的生产就绪

将 AI 智能体从概念化推向可靠的生产部署,需要一种超越传统软件测试局限性的复杂评估策略。Strands Evals 正是提供了这一点:一个实用、结构化的框架,它承认 AI 智能体固有的非确定性和复杂的自适应特性。通过清晰地定义 案例 进行评估,通过 实验 进行编排,并应用细致的 评估器(尤其是那些由 LLM 提供支持的定性判断评估器),Strands Evals 使开发人员能够系统地评估性能。

任务函数 的多功能性,支持用于快速开发的实时在线评估以及对历史数据的离线分析,进一步巩固了其在智能体整个生命周期中的实用性。这种综合方法确保了 AI 智能体不仅功能完备,而且有用、连贯且稳健,为它们成功集成到关键生产环境提供了必要的信心。在当今快速发展的技术格局中,对于任何认真构建、部署和维护高质量、生产就绪 AI 智能体的人来说,采用像 Strands Evals 这样的框架至关重要。

常见问题

What fundamental challenge do AI agents pose for traditional software testing methodologies?
AI agents, by their inherent nature, are flexible, adaptive, and highly context-aware, making their outputs non-deterministic. Unlike traditional software where the same input reliably yields the same expected output, AI agents generate natural language responses and make decisions that can vary even with identical inputs. This variability means that conventional assertion-based testing, which relies on precise, predictable outcomes, is inadequate. Agents' ability to use tools, retrieve information, and engage in multi-turn conversations further complicates evaluation, requiring a shift from simple keyword comparisons to nuanced, judgment-based assessments that can handle the fluidity and creativity of AI-driven interactions. This necessitates specialized frameworks like Strands Evals to systematically gauge quality dimensions beyond strict determinism.
How does Strands Evals address the non-deterministic nature of AI agent outputs?
Strands Evals tackles the non-deterministic challenge by introducing a framework centered on judgment-based evaluation, primarily leveraging large language models (LLMs) as evaluators. Instead of relying on strict assertion checks, LLM-based evaluators can make nuanced assessments of qualitative aspects such as helpfulness, coherence, relevance, and faithfulness of agent responses. The framework organizes evaluation into Cases (individual scenarios), Experiments (collections of cases and evaluators), and Evaluators (the judging mechanism), allowing for systematic yet flexible assessment. This approach moves beyond simple string comparisons to understand the subjective quality of agent interactions, ensuring that even varied but valid outputs are correctly recognized as successful.
Explain the core concepts of Strands Evals: Cases, Experiments, and Evaluators.
Strands Evals builds upon three foundational concepts to enable systematic AI agent evaluation. A **Case** serves as the atomic unit of testing, defining a single test scenario. It includes the user input (e.g., a query), optional expected outputs, anticipated tool usage sequences (trajectories), and relevant metadata. An **Experiment** functions as a test suite, bundling multiple Cases together with one or more Evaluators. It orchestrates the entire evaluation process, running the agent against each Case and applying the configured Evaluators. Finally, **Evaluators** act as the 'judges,' assessing the agent's actual output and trajectory against the expectations. Crucially, Strands Evals primarily uses LLM-based Evaluators to make qualitative judgments on attributes like helpfulness and coherence, which are difficult to quantify with traditional assertion methods, providing a flexible yet rigorous assessment.
What is the purpose of the Task Function in Strands Evals, and how do online and offline evaluation differ?
The Task Function in Strands Evals is a critical callable component that bridges your AI agent's execution environment with the evaluation system. Its purpose is to receive a Case (a test scenario) and return the agent's results (output and execution trace) in a format suitable for evaluation. This function enables two distinct patterns: **Online Evaluation** involves invoking your agent live during the evaluation run. Here, the Task Function creates an agent, feeds it the case input, and captures its real-time response and execution trace. This is ideal for development, testing immediate changes, or integrating into CI/CD pipelines. In contrast, **Offline Evaluation** works with historical data. The Task Function retrieves previously recorded agent traces from logs or databases, parsing them into the expected format. This is highly effective for analyzing production traffic, performing historical performance analysis, or comparing different agent versions against consistent real-world interactions, offering flexibility without requiring live agent invocation.
Why are LLM-based evaluators crucial for assessing AI agents effectively?
LLM-based evaluators are crucial because they overcome the limitations of traditional, assertion-based testing when assessing AI agents. Agents often produce natural language outputs and make context-dependent decisions, meaning there isn't always one single 'correct' answer that can be checked with a simple string comparison. LLM-based evaluators, leveraging their understanding of language and context, can make nuanced judgments about subjective qualities such as a response's helpfulness, coherence, relevance, or faithfulness to source material. They can discern whether an agent's varied but valid output still meets user goals or maintains context across multi-turn conversations. This capability is essential for systematically measuring the qualitative dimensions of agent performance that are vital for real-world utility and user satisfaction, ensuring agents are not only factually accurate but also user-friendly and effective.

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