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ToolSimulator: scalable tool testing for AI agents

Machine Learning Blog



This article introduces ToolSimulator, an LLM-powered framework within Strands Evals for safely testing AI agents that use external tools at scale.

  • Replaces risky live API calls with intelligent, adaptive LLM-based simulations
  • Maintains consistent state across multi-turn workflows without touching production systems
  • Validates tool responses against Pydantic schemas to catch malformed outputs
  • Generates realistic, context-appropriate responses based on tool schemas and agent inputs
  • Supports independent simulator instances for parallel testing configurations
  • Integrates seamlessly with Strands Evals evaluation pipelines and telemetry
  • Available in Strands Evals SDK; no AWS account required for local testing

ToolSimulator enables developers to test complex agent workflows safely, catch integration bugs early, and deploy production-ready agents without managing test infrastructure or risking unintended side effects.



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