Read tools carry readOnlyHint: true. Draft tools carry readOnlyHint: false, destructiveHint: false and idempotentHint: true, which is what makes clients such as ChatGPT and Claude ask the user before each call.
Draft tools only create drafts: an open purchase order that is never submitted, products added as drafts that are never activated, or a new supplier. Each returns what it made and a link to review it in Apex. No tool can submit or send a purchase order, contact a supplier, spend money, create or send a shipment, change a live price or repricer setting or delete anything.
create_draft_purchase_order accepts a requestId. The same id within 24 hours returns the first order instead of creating a second.