diff --git a/kong/mcp/ai-mcp-proxy.yaml b/kong/mcp/ai-mcp-proxy.yaml
index fe36bf4..569d0e7 100644
--- a/kong/mcp/ai-mcp-proxy.yaml
+++ b/kong/mcp/ai-mcp-proxy.yaml
@@ -72,25 +72,50 @@ config:
         required: true
         content:
           application/json:
+            # Mirrors ProductRequest in catalog-api/openapi.yaml. It has to:
+            # this schema is the only thing the caller sees, so anything it
+            # omits the caller cannot send. `productcode` was missing and is
+            # required by the API, which made this tool impossible to call
+            # successfully — every attempt came back
+            # {"productcode":["This field is required."]}, and a caller that
+            # tried to supply it anyway was rejected earlier still, here.
             schema:
               type: object
               properties:
+                productcode:
+                  type: string
+                  maxLength: 15
+                  description: Unique catalog identifier, e.g. S10_1949. Ask for it; do not invent one.
                 productname:
                   type: string
+                  maxLength: 70
                 productline:
                   type: string
+                  description: Must be an existing product line, as returned by list-productlines.
                 productscale:
                   type: string
+                  maxLength: 10
                 productvendor:
                   type: string
+                  maxLength: 50
                 productdescription:
                   type: string
                 quantityinstock:
                   type: integer
+                  minimum: -32768
+                  maximum: 32767
                 buyprice:
                   type: string
+                  description: Decimal as a string, at most two places, e.g. "50.00".
                 msrp:
                   type: string
+                  description: Decimal as a string, at most two places, e.g. "99.00".
               required:
+                - productcode
                 - productname
                 - productline
+                - productscale
+                - productvendor
+                - productdescription
+                - buyprice
+                - msrp