diff --git a/cpp/include/cuvs/neighbors/cagra.hpp b/cpp/include/cuvs/neighbors/cagra.hpp
index 0035930b8..241e411d7 100644
--- a/cpp/include/cuvs/neighbors/cagra.hpp
+++ b/cpp/include/cuvs/neighbors/cagra.hpp
@@ -248,6 +248,10 @@ struct extend_params {
    * 0. */
   uint32_t max_chunk_size = 0;
 
+  /** The dataset chunk where the maximum size is defined by `max_chunk_size` is divided by
+   * sub-chunks to limit the working memory usage. This is the knob to control the working memory
+   * usage. Large working memory size can result in high throughput.
+   * */
   uint32_t max_working_device_memory_size_in_megabyte = 512;
 };