AWS Strands Agents vs LlamaIndex: Which Agent Framework to Use?

AWS Strands Agents AWS Strands Agents is a lightweight, model-driven Python SDK for building agents released by AWS in May 2025.

LlamaIndex LlamaIndex started as a RAG framework — connect your data, query it with an LLM.

Both wrap the same underlying agent pattern — an LLM call, a tool dispatch, a loop — in different abstractions. The choice between them is mostly about which mental model and ecosystem fits the team you have, not which one is technically more capable.

Pick AWS Strands Agents if aWS Strands fits AWS-heavy teams that want a thin SDK, native MCP, and a hosted runtime via Bedrock AgentCore. The model-driven design is genuinely lighter than LangChain — but for teams not on AWS, plain Python is closer to what Strands is doing than any other framework on this list. AWS Strands Agents is the right fit when the tradeoffs in its intro line up with how your team actually wants to work day-to-day; LlamaIndex would force you to translate.

Pick LlamaIndex if llamaIndex adds genuine value when your agent needs to query structured or unstructured data as part of its reasoning — that's the index-as-tool pattern, and it's well-executed. But if you're building a general-purpose agent that doesn't need RAG, the agent framework is overhead. The plain Python version of the agent loop is the same 60 lines either way. LlamaIndex is the right fit when the tradeoffs in its intro line up with how your team actually wants to work day-to-day; AWS Strands Agents would force you to translate.

Both AWS Strands Agents and LlamaIndex pull in a class hierarchy and a dependency tree to wrap what is, at the core, an HTTP POST in a while loop. If your use case is straightforward — one provider, a handful of tools, a single agent — the framework cost may exceed the framework benefit. The lesson below shows the same pattern in ~60 lines without either dependency.