Design Gemini-powered Reasoning Agent

Design a LlamaIndex agent that leverages Gemini 2.5 Pro for its primary reasoning engine. The agent should be able to receive a mathematical statement, query the `VectorStoreIndex` for relevant context, and then use Gemini to construct a step-by-step proof. Implement at least two tools within the LlamaIndex agent: one to `search_math_index` (which queries your ChromaDB-backed `VectorStoreIndex`) and another to `output_final_proof` (which formats the Gemini-generated proof). Include the agent initialization and tool definitions.