diff --git a/lib/galaxy/tools/xsd/galaxy.xsd b/lib/galaxy/tools/xsd/galaxy.xsd
index 47ba3be03de..e056c6ed3a3 100644
--- a/lib/galaxy/tools/xsd/galaxy.xsd
+++ b/lib/galaxy/tools/xsd/galaxy.xsd
@@ -2656,7 +2656,8 @@ be escaped with a backslash (``\``) when appearing in ``command`` or ``configfil
 Name | Description
 ---- | -----------
 ``\${GALAXY_SLOTS:-4}`` | Number of cores/threads allocated by the job runner or resource manager to the tool for the given job (here 4 is the default number of threads to use if running via custom runner that does not configure GALAXY_SLOTS or in an older Galaxy runtime).
-``\$GALAXY_MEMORY_MB`` | Amount of memory in megabytes (1024^2 bytes) allocated by the administrator (via the resource manager) to the tool for the given job. If unset, tools should not attempt to limit memory usage.
+``\$GALAXY_MEMORY_MB`` | Total amount of memory in megabytes (1024^2 bytes) allocated by the administrator (via the resource manager) to the tool for the given job. If unset, tools should not attempt to limit memory usage.
+``\$GALAXY_MEMORY_MB_PER_SLOT`` | Amount of memory per slot in megabytes (1024^2 bytes) allocated by the administrator (via the resource manager) to the tool for the given job. If unset, tools should not attempt to limit memory usage.
 
 See the [Planemo docs](https://planemo.readthedocs.io/en/latest/writing_advanced.html#cluster-usage)
 on the topic of ``GALAXY_SLOTS`` for more information and examples.