diff --git a/etc/icinga2/zones.d/README b/etc/icinga2/zones.d/README
index ceff6bd8c..bbce30fd6 100644
--- a/etc/icinga2/zones.d/README
+++ b/etc/icinga2/zones.d/README
@@ -1,2 +1,11 @@
-This directory contains configuration files for cluster zones. If you're not
-running a cluster you can safely ignore this directory.
+This directory contains zone directories used for
+distributed monitoring with the cluster config sync.
+
+Use this for the following scenarios:
+
+- Master with Agents
+- HA Masters with Agents
+- Masters, Satellites and Agents
+
+Please check the documentation for more details:
+https://icinga.com/docs/icinga2/latest/doc/06-distributed-monitoring/
diff --git a/lib/icinga/checkable.cpp b/lib/icinga/checkable.cpp
index 55bbfeb16..04e462951 100644
--- a/lib/icinga/checkable.cpp
+++ b/lib/icinga/checkable.cpp
@@ -53,7 +53,7 @@ void Checkable::OnAllConfigLoaded()
 			}
 		} else {
 			BOOST_THROW_EXCEPTION(ValidationError(this, { "command_endpoint" },
-				"Command endpoint must not be set."));
+				"Checkable with command endpoint requires a zone. Please check the troubleshooting documentation."));
 		}
 	}
 }