Implement custom authentication for tools integration using request Lambda interceptor in AgentCore Gateway

This article demonstrates how to use a request Lambda interceptor in Amazon Bedrock AgentCore Gateway to implement custom authentication for legacy tools using HTTP Basic Auth with credentials from AWS Secrets Manager.

• Request Lambda interceptor validates inbound JWT tokens as a defense-in-depth measure before forwarding requests
• Retrieves system service account credentials from Secrets Manager encrypted with customer-managed KMS keys
• Constructs compliant Basic Auth headers without exposing credentials to the AI agent
• Isolates credential handling from agent runtime to mitigate prompt injection risks
• Requires TLS communication and compensating controls since Basic Auth transmits Base64-encoded credentials
• Enables interim integration with legacy authentication systems while modernizing to OAuth 2.0 or SAML

This pattern bridges modern AI agents with legacy tool APIs by centralizing authentication transformation in a deterministic Lambda function, keeping credentials isolated from non-deterministic model behavior.