diff --git a/products/cloudbuild/api.yaml b/products/cloudbuild/api.yaml
index 531e4dcb0a24..09c51050f666 100644
--- a/products/cloudbuild/api.yaml
+++ b/products/cloudbuild/api.yaml
@@ -80,6 +80,9 @@ objects:
         item_type: Api::Type::String
         input: true
         description: |
+          ignoredFiles and includedFiles are file glob matches using http://godoc/pkg/path/filepath#Match
+          extended with support for "**".
+
           If any of the files altered in the commit pass the ignoredFiles filter
           and includedFiles is empty, then as far as this filter is concerned, we
           should trigger the build.