Claude Agent with Retrieval Tool Implementation

Initialize your **Claude Agent** using the **Claude Agents SDK** with **Claude Opus 4.1**. Define a custom tool (`retrieve_document_chunks(query: str) -> List[str]`) that queries your Weaviate instance and returns the top-k most relevant document chunks. The agent should be able to use this tool when asked to analyze a document or a specific legal concept. Provide the agent initialization code and the tool definition.