diff --git a/lib/galaxy/tools/xsd/galaxy.xsd b/lib/galaxy/tools/xsd/galaxy.xsd
index 1b5a14b6ad2..e22f2e80000 100644
--- a/lib/galaxy/tools/xsd/galaxy.xsd
+++ b/lib/galaxy/tools/xsd/galaxy.xsd
@@ -1340,6 +1340,11 @@ The functional test tool
 provides a demonstration of using this tag.
 
 ```xml
+<outputs>
+    <data format="tabular" name="sample">
+      <discover_datasets pattern="(?P&lt;designation&gt;.+)\.report\.tsv" ext="tabular" visible="true" assign_primary_output="true" />
+    </data>
+</outputs>
 <test>
   <param name="num_param" value="7" />
   <param name="input" ftype="txt" value="simple_line.txt"/>
@@ -1358,6 +1363,7 @@ provides a demonstration of using this tag.
 </test>
 ```
 
+Note that this tool uses ``assign_primary_output="true"`` for ``<discover_data_sets>``. Hence, the content of the first discovered dataset (which is the first in the alphabetically sorted list of discovered designations) is checked directly in the ``<output>`` tag of the test.
 ]]></xs:documentation>
     </xs:annotation>
     <xs:complexContent>