You are designing a prompt for an AI assistant to answer the user query: 'What is the current stock price of Company XYZ and how has it performed over the last year?' The system has access to pre-retrieved annual performance reports for Company XYZ. It can also use an external tool to get the live, current stock price. Write a single, effective prompt that instructs the assistant on how to use both the provided information and the external tool to formulate a comprehensive answer.