diff --git a/mediapipe/framework/tool/executor_util.h b/mediapipe/framework/tool/executor_util.h
index 3167cdd04..5fb25da74 100644
--- a/mediapipe/framework/tool/executor_util.h
+++ b/mediapipe/framework/tool/executor_util.h
@@ -22,6 +22,10 @@ namespace mediapipe {
 
 namespace tool {
 // Ensures the default executor's stack size is at least min_stack_size.
+//
+// Note that this will also initialize the default executor; any configuration
+// changes, such as num_threads, should be done to the config before calling
+// this.
 void EnsureMinimumDefaultExecutorStackSize(int32 min_stack_size,
                                            CalculatorGraphConfig* config);
 }  // namespace tool