diff --git a/src/caosdb/yamlapi.py b/src/caosdb/yamlapi.py
index b2e527983cbbeca2ee71a63e87f487d24d7c0301..ae8c760db82b011bc9988a084e8c2bc30055d41d 100644
--- a/src/caosdb/yamlapi.py
+++ b/src/caosdb/yamlapi.py
@@ -73,6 +73,11 @@ def dict_to_xml(d):
 
 
 def yaml_to_xml(yamlstr):
+    """
+    yamlstr: The string to load the yaml document from.
+    Loads a yaml document from yamlstr and converts
+    it to XML.
+    """
     return dict_to_xml(yaml.load(yamlstr))