ZIT prompting guide and tweaks

tools/generate_image.py

@@ -174,7 +174,7 @@ async def handle(args: Dict[str, Any]) -> List[Dict[str, Any]]:
                 except (ValueError, AttributeError):
                     raise ToolError(f"Invalid resolution format for preset '{res_preset_name}': {res_val_str}. Expected 'WidthxHeight'.")
             else:
-                raise ToolError(f"Resolution preset '{res_preset_name}' not found for this model. Available: {', '.join(res_set.keys())}")
+                raise ToolError(f"Resolution preset '{res_preset_name}' not found for this model. You MUST call get_model_info with this model_name to see the available resolution presets.")
         else:
             raise ToolError(f"No resolution set configured for model '{model_name}'.")