Build custom code-based evaluators in Amazon Bedrock AgentCore

This article explains how to build custom code-based evaluators in Amazon Bedrock AgentCore for production-grade agent quality assessment.

• Custom code-based evaluators use AWS Lambda functions for deterministic quality checks
• Four evaluator types demonstrated: schema validation, price accuracy, workflow compliance, PII detection
• Evaluators operate at TRACE, TOOL_CALL, or SESSION levels for different granularities
• On-demand evaluation supports development, regression testing, and CI/CD deployment gates
• Online evaluation continuously samples live production traffic with configurable sampling rates
• Results emit as CloudWatch metrics for dashboards and alarms
• Market Trends Agent example shows financial domain-specific quality requirements
• Single evaluator registration works across development, testing, and production monitoring

Custom code-based evaluators enable deterministic quality checks for agents, complementing LLM-as-a-Judge evaluators for subjective dimensions.