Comprehensive .NET toolkit for AI agent evaluation featuring fluent assertions, stochastic testing, model comparison, and security evaluation built specifically for Microsoft Agent Framework
A .NET framework for testing whether AI agents work correctly, stay secure, and deliver quality answers before you deploy them to production.
AgentEval is the comprehensive .NET evaluation toolkit for AI agents, designed to be what RAGAS and DeepEval are for Python, but built natively for the Microsoft ecosystem. Specifically developed for Microsoft Agent Framework (MAF) and Microsoft.Extensions.AI, AgentEval provides sophisticated evaluation capabilities including tool usage validation, RAG quality metrics, stochastic evaluation, and model comparison with enterprise-grade fluent assertion syntax.
The framework's standout feature is its ability to assert on tool chains like requirements using intuitive Should() syntax, allowing developers to verify that agents call tools in the correct sequence with proper arguments and timing. This capability is crucial for complex agent workflows where the order and accuracy of tool execution determines success or failure.
AgentEval's stochastic evaluation capability addresses the non-deterministic nature of LLM responses by running the same evaluation multiple times and asserting on success rates rather than single runs, providing statistically meaningful results. This approach recognizes that LLMs can produce different outputs for identical inputs, making single-run evaluations unreliable for production assessment.
The platform includes innovative trace record/replay functionality that captures live API interactions once and replays them infinitely without API costs, enabling consistent CI/CD evaluation workflows. This feature eliminates the variability and expense of live API calls during testing while maintaining realistic evaluation scenarios.
AgentEval's Red Team Security module evaluates against 192 attack probes covering 6 OWASP LLM Top 10 vulnerabilities with MITRE ATLAS technique mapping, testing for prompt injection, jailbreaks, PII leakage, and other security vulnerabilities. This comprehensive security evaluation is essential for enterprise AI applications where security breaches can have severe consequences.
Model comparison features provide side-by-side evaluation of different models with cost-quality recommendations, helping teams make data-driven decisions about which models to deploy. The platform can compare performance across GPT-4o, Claude, and other major providers while analyzing the cost-benefit tradeoffs.
With MIT licensing and a commitment to remaining open source forever, AgentEval offers full type safety, compile-time error checking, and deep IDE integration that leverages the strengths of the .NET ecosystem for enterprise AI agent development. This makes it particularly valuable for organizations already invested in Microsoft's technology stack.
Compared to Python alternatives like DeepEval or LangSmith, AgentEval provides native .NET integration with superior type safety and enterprise development practices, making it ideal for organizations prioritizing reliability and maintainability in their AI evaluation infrastructure.
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AgentEval fills a critical gap: production-grade AI agent testing for the .NET ecosystem. The stochastic evaluation, red team probes, and trace replay are genuinely useful. Limited to .NET, which narrows the audience but deepens the value for Microsoft-stack teams.
Uses a Should() syntax to assert that agents call tools in a required order with specific arguments, e.g., HaveCalledTool("AuthenticateUser").BeforeTool("FetchUserData").WithArgument("method", "OAuth2"). This replaces regex log-parsing with type-safe, IDE-autocompleted assertions that surface failures at compile time rather than in production.
Executes the same test case N times (configurable via StochasticOptions(Runs: 10, SuccessRateThreshold: 0.85)) and asserts on aggregate statistics like success rate and standard deviation. This addresses the fundamental non-determinism of LLMs, replacing lucky-single-run pass/fail with statistically meaningful verdicts.
The TraceRecordingAgent wraps a live agent once to capture all API interactions to JSON, after which TraceReplayingAgent returns identical responses forever with zero API cost. This enables deterministic CI runs, lets teams reproduce production failures offline, and eliminates flaky tests caused by live LLM variability.
Runs 192 attack probes across 9 categories including Prompt Injection, Jailbreaks, PII Leakage, and Excessive Agency, covering 6 of the OWASP LLM Top 10 2025 with MITRE ATLAS technique mapping. A one-line QuickRedTeamScanAsync() produces a 0–100 security score, and AttackPipeline.Create() allows granular intensity control plus PDF export for compliance reporting.
CompareModelsAsync takes a list of model factories, test cases, and metrics (ToolSuccessMetric, RelevanceMetric, etc.) and returns a ranked markdown leaderboard. Output includes tool accuracy percentages, relevance scores, and cost per 1K requests, plus automated recommendations like "GPT-4o Mini — 87.5% accuracy at 50x lower cost" to drive data-driven model selection.
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AgentEval launched in 2025–2026 targeting the newly released Microsoft Agent Framework (MAF) and Microsoft.Extensions.AI. Recent additions include the 192-probe Red Team Security module with OWASP LLM Top 10 2025 coverage and MITRE ATLAS technique mapping, a universal IChatClient.AsEvaluableAgent() cross-framework bridge, a Semantic Kernel integration bridge, and the agenteval CLI tool. Commercial/Enterprise add-ons are on the roadmap but not yet released.
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