Discover tools at runtime with AWS Agent Registry

AWS published a walkthrough of using AWS Agent Registry so an orchestrator agent discovers MCP servers and A2A agents at runtime instead of hardcoding them. The sample deploys an order-management MCP server through Amazon Bedrock AgentCore Gateway, two A2A agents on AgentCore runtime, and an orchestrator that searches approved records, builds request-scoped clients, and tears them down after each turn. Registry search returns descriptors but not invocation credentials, which are fetched separately via Cognito OAuth and boto3 IAM signing.