diff --git a/src/app/api/mcp/route.ts b/src/app/api/mcp/route.ts
index 29ff226..aee971b 100644
--- a/src/app/api/mcp/route.ts
+++ b/src/app/api/mcp/route.ts
@@ -1717,7 +1717,7 @@ const tools = [
   {
     name: "collection_confirm.ai_check",
     description:
-      "Run the AI document check on one Collection Confirm card (one PO) now: reads the driver's invoice/delivery-note photos, pairs document lines with PO lines, fills an empty line SKU and records `ai_check` per line. Never changes cost, quantities, status or invoice details, and never overwrites a human-set SKU.",
+      "Run the AI document check on one Collection Confirm card (one PO) now: reads the driver's invoice/delivery-note photos, pairs document lines with PO lines, fills an empty line SKU and records `ai_check` per line. When a line it is sure about shows a discount on a tax invoice and the cost isn't the price after discount, it sets the cost to that price (with a note). Otherwise never changes cost; never changes quantities, status or invoice details, and never overwrites a human-set SKU.",
     inputSchema: {
       type: "object",
       required: ["po_number"],