diff --git a/docs/source/example_eval.rst b/docs/source/example_eval.rst
index 5287af5..0b29e7f 100644
--- a/docs/source/example_eval.rst
+++ b/docs/source/example_eval.rst
@@ -20,7 +20,7 @@ To generate a `GraspGroup` and save it, you can directly input a 2D numpy array
                 ))
   gg.save_npy(save_path)
 
-where your algorithm predicts N grasp poses for an image. For the meaning of each entry, you should refer to the doc for Grasp Label Format-API Loaded Labels
+where your algorithm predicts N grasp poses for an image. For the `object_id`, you can simply input `0`. For the meaning of other entries, you should refer to the doc for Grasp Label Format-API Loaded Labels
 
 The file structure of dump folder should be as follows: