diff --git a/components/renku_data_services/session/api.spec.yaml b/components/renku_data_services/session/api.spec.yaml
index bb3a9f18c..cbdcd29ef 100644
--- a/components/renku_data_services/session/api.spec.yaml
+++ b/components/renku_data_services/session/api.spec.yaml
@@ -722,7 +722,7 @@ components:
       maxLength: 500
       example: "https://github.com/voila-gallery/gaussian-density"
     Revision:
-      description: The revision of the repository used as a basis for a custom builder
+      description: The revision of the repository used as a basis for a custom builder. This can be a git branch, a git tag or a git commit.
       type: string
       maxLength: 100
       example: "main"