diff --git a/_assets/ci/get-docker-image-tag.sh b/_assets/ci/get-docker-image-tag.sh
index 9360bf1bf..6183e11ec 100755
--- a/_assets/ci/get-docker-image-tag.sh
+++ b/_assets/ci/get-docker-image-tag.sh
@@ -1,6 +1,11 @@
 #!/usr/bin/env bash
 #
-# Description
+# Creates a string in a format: $GIT_SHA[:8][-$BUILD_TAGS]
+# where $BUILD_TAGS is optional and if present all spaces
+# are replaced by a hyphen (-).
+#
+# For example: BUILD_TAGS="tag1 tag2" ./_assets/ci/get-docker-image-tag.sh
+# will produce "12345678-tag1-tag2".
 
 set -e -o pipefail