Complete a paid purchase of a book. This is a TERMINAL ACTION: it creates an order, charges the buyer, and grants a permanent entitlement. Only call this when the user has EXPLICITLY requested to buy. Never call as part of browsing, price comparison, or information gathering — prices are already visible in search_books results, and free previews are available via get_book_preview. If the user says 'don't buy', 'just compare', 'just tell me the price', or similar — do NOT call this tool. If the user requests an action that requires owning a book they don't own (e.g. commenting on an unowned book), do NOT silently purchase it on their behalf. Instead, tell the user the purchase requirement and ask them to confirm. Spending money is never an inferred default.
Connector