Agentic retrieval for Amazon Bedrock Managed Knowledge Base
AWS Omar Elkharbotly
Amazon Bedrock Managed Knowledge Bases now offers agentic retrieval through the AgenticRetrieveStream API, which decomposes multi-part questions into sub-queries and iterates over retrieval rather than returning results from a single similarity search. The API costs $4 per 1,000 agentic retrieval calls plus $1 per 1,000 underlying Retrieve API calls when using the managed model. This approach improves performance on comparative, exploratory, and multi-knowledge-base queries by letting a foundation model plan retrieval steps and judge when sufficient evidence has been gathered, replacing custom agent frameworks previously needed for such questions.
Why it matters
This post focuses on why classic retrieval falls short on multi-part questions, how the AgenticRetrieveStream API works (including request construction and trace parsing), and when to choose it over the standard Retrieve API.