diff --git a/apps/emqx/src/emqx_schema.erl b/apps/emqx/src/emqx_schema.erl
index 065c9b54b..9f9d7609a 100644
--- a/apps/emqx/src/emqx_schema.erl
+++ b/apps/emqx/src/emqx_schema.erl
@@ -954,7 +954,8 @@ fields("ws_opts") ->
                     default => false,
                     desc =>
                         "If <code>true</code>, compress WebSocket messages using <code>zlib</code>.<br/>\n"
-                        " The configuration items under <code>deflate_opts</code> belong to the compression-related parameter configuration."
+                        "The configuration items under <code>deflate_opts</code> "
+                        "belong to the compression-related parameter configuration."
                 }
             )},
         {"idle_timeout",
@@ -1414,10 +1415,7 @@ fields("sysmon_vm") ->
             sc(
                 hoconsc:union([disabled, duration()]),
                 #{
-                    desc =>
-                        "Enable Long GC monitoring.<br/>\n"
-                        " Notice: don't enable the monitor in production for:<br/>\n"
-                        " https://github.com/erlang/otp/blob/feb45017da36be78d4c5784d758ede619fa7bfd3/erts/emulator/beam/erl_gc.c#L421"
+                    desc => "Enable Long GC monitoring.<br/>"
                 }
             )},
         {"long_schedule",
@@ -1677,7 +1675,8 @@ mqtt_listener() ->
                     duration(),
                     #{
                         desc =>
-                            "Timeout for proxy protocol. EMQX will close the TCP connection if proxy protocol packet is not received within the timeout."
+                            "Timeout for proxy protocol. EMQX will close the TCP connection "
+                            "if proxy protocol packet is not received within the timeout."
                     }
                 )},
             {?EMQX_AUTHENTICATION_CONFIG_ROOT_NAME,
@@ -1845,7 +1844,15 @@ common_ssl_opts_schema(Defaults) ->
         {"depth",
             sc(
                 integer(),
-                #{default => Df("depth", 10)}
+                #{
+                    default => Df("depth", 10),
+                    desc =>
+                        "Maximum number of non-self-issued intermediate certificates that can follow "
+                        "the peer certificate in a valid certification path. "
+                        "So, if depth is 0 the PEER must be signed by the trusted ROOT-CA directly; "
+                        "if 1 the path can be PEER, CA, ROOT-CA; if 2 the path can be PEER, CA, CA, ROOT-CA, "
+                        "and so on. The default value is 10."
+                }
             )},
         {"password",
             sc(
diff --git a/apps/emqx_exhook/src/emqx_exhook_schema.erl b/apps/emqx_exhook/src/emqx_exhook_schema.erl
index 6cc1ebfcd..91e05b951 100644
--- a/apps/emqx_exhook/src/emqx_exhook_schema.erl
+++ b/apps/emqx_exhook/src/emqx_exhook_schema.erl
@@ -61,7 +61,7 @@ fields(server) ->
                             })}
     , {failed_action, failed_action()}
     , {ssl,
-       sc(ref(ssl_conf), #{})}
+       sc(ref(ssl_conf), #{desc => "SSL client config"})}
     , {auto_reconnect,
        sc(hoconsc:union([false, duration()]),
           #{ default => "60s"
diff --git a/apps/emqx_gateway/src/emqx_gateway_schema.erl b/apps/emqx_gateway/src/emqx_gateway_schema.erl
index b01df7bb8..9b7f80d19 100644
--- a/apps/emqx_gateway/src/emqx_gateway_schema.erl
+++ b/apps/emqx_gateway/src/emqx_gateway_schema.erl
@@ -221,7 +221,10 @@ option. The indicator can be set to:
     * qos0: If the publish request is non-confirmable
     * qos1: If the publish request is confirmable"
            })}
-    , {listeners, sc(ref(udp_listeners))}
+    , {listeners,
+       sc(ref(udp_listeners),
+          #{ desc =>"Listeners (UDP) for CoAP service"
+           })}
     ] ++ gateway_common_options();
 
 fields(lwm2m) ->