diff --git a/src/server/engine_shard_set.cc b/src/server/engine_shard_set.cc
index f54e4e1fd..8d9d336f0 100644
--- a/src/server/engine_shard_set.cc
+++ b/src/server/engine_shard_set.cc
@@ -23,7 +23,11 @@ extern "C" {
 
 using namespace std;
 
-ABSL_FLAG(string, spill_file_prefix, "", "");
+ABSL_FLAG(string, spill_file_prefix, "",
+          "Experimental flag. Enables tiered storage if set. "
+          "The string denotes the path and prefix of the files "
+          " associated with tiered storage. E.g,"
+          "spill_file_prefix=/path/to/file-prefix");
 
 ABSL_FLAG(uint32_t, hz, 100,
           "Base frequency at which the server performs other background tasks. "