diff --git a/lib/active_agent/providers/mock/request.rb b/lib/active_agent/providers/mock/request.rb
index 57059c58..eac8a754 100644
--- a/lib/active_agent/providers/mock/request.rb
+++ b/lib/active_agent/providers/mock/request.rb
@@ -22,16 +22,13 @@ class Request < Common::BaseModel
         attribute :stream, :boolean, default: false
         attribute :tools # Array of tool definitions
         attribute :tool_choice # Tool choice configuration
+        attribute :response_format
 
         # Common Format Compatibility
         def message=(value)
           self.messages ||= []
           self.messages << value
         end
-
-        def response_format
-          { type: "text" }
-        end
       end
     end
   end