diff --git a/apps/emqx_conf/src/emqx_conf_schema.erl b/apps/emqx_conf/src/emqx_conf_schema.erl
index 7fb9d730a..826b73461 100644
--- a/apps/emqx_conf/src/emqx_conf_schema.erl
+++ b/apps/emqx_conf/src/emqx_conf_schema.erl
@@ -651,10 +651,12 @@ fields("log_rotation") ->
     [ {"enable",
        sc(boolean(),
           #{ default => true
+           , desc => "Enable log rotation feature."
            })}
     , {"count",
        sc(range(1, 2048),
           #{ default => 10
+           , desc => "Maximum number of log files."
            })}
     ];
 
@@ -662,18 +664,23 @@ fields("log_overload_kill") ->
     [ {"enable",
        sc(boolean(),
           #{ default => true
+           , desc => "Enable log handler overload kill feature."
            })}
     , {"mem_size",
        sc(emqx_schema:bytesize(),
           #{ default => "30MB"
+           , desc => "Maximum memory size that the handler process is allowed to use."
            })}
     , {"qlen",
        sc(integer(),
           #{ default => 20000
+           , desc => "Maximum allowed queue length."
            })}
     , {"restart_after",
        sc(hoconsc:union([emqx_schema:duration(), infinity]),
           #{ default => "5s"
+           , desc => "If the handler is terminated, it restarts automatically after a "
+                     "delay specified in milliseconds. The value `infinity` prevents restarts."
            })}
     ];
 
@@ -681,14 +688,20 @@ fields("log_burst_limit") ->
     [ {"enable",
        sc(boolean(),
           #{ default => true
+           , desc => "Enable log burst control feature."
            })}
     , {"max_count",
        sc(integer(),
           #{ default => 10000
+           , desc => "Maximum number of log events to handle within a `window_time` interval. "
+                     "After the limit is reached, successive events are dropped "
+                     "until the end of the `window_time`."
            })}
     , {"window_time",
        sc(emqx_schema:duration(),
-          #{default => "1s"})}
+          #{ default => "1s"
+           , desc => "See `max_count`."
+           })}
     ];
 
 fields("authorization") ->
@@ -801,6 +814,7 @@ log_handler_common_confs() ->
     [ {"enable",
        sc(boolean(),
           #{ default => false
+           , desc => "Enable this log handler."
            })}
     , {"level",
        sc(log_level(),
@@ -811,6 +825,7 @@ log_handler_common_confs() ->
     , {"time_offset",
        sc(string(),
           #{ default => "system"
+           , desc => "The time offset to be used when formatting the timestamp."
            })}
     , {"chars_limit",
        sc(hoconsc:union([unlimited, range(1, inf)]),
@@ -833,24 +848,34 @@ log_handler_common_confs() ->
     , {"sync_mode_qlen",
        sc(integer(),
           #{ default => 100
+           , desc => "As long as the number of buffered log events is lower than this value, "
+                     "all log events are handled asynchronously."
            })}
     , {"drop_mode_qlen",
        sc(integer(),
           #{ default => 3000
+           , desc => "When the number of buffered log events is larger than this value, "
+                     "the new log events are dropped.<br/>"
+                     "When drop mode is activated or deactivated, a message is printed in "
+                     "the logs."
            })}
     , {"flush_qlen",
        sc(integer(),
           #{ default => 8000
+           , desc => "If the number of buffered log events grows larger than this threshold, "
+                     "a flush (delete) operation takes place. "
+                     "To flush events, the handler discards the buffered log messages without logging."
            })}
     , {"overload_kill",
-       sc(ref("log_overload_kill"),
-          #{})}
+       sc(ref("log_overload_kill"), #{})}
     , {"burst_limit",
-       sc(ref("log_burst_limit"),
-          #{})}
+       sc(ref("log_burst_limit"), #{})}
     , {"supervisor_reports",
        sc(hoconsc:enum([error, progress]),
           #{ default => error
+           , desc => "Type of supervisor reports that are logged.\n"
+                     " - `error`: only log errors in the Erlang processes.\n"
+                     " - `progress`: log process startup."
            })}
     , {"max_depth",
        sc(hoconsc:union([unlimited, non_neg_integer()]),
diff --git a/apps/emqx_prometheus/src/emqx_prometheus_schema.erl b/apps/emqx_prometheus/src/emqx_prometheus_schema.erl
index 17387e06d..5434ef1f1 100644
--- a/apps/emqx_prometheus/src/emqx_prometheus_schema.erl
+++ b/apps/emqx_prometheus/src/emqx_prometheus_schema.erl
@@ -28,9 +28,21 @@ namespace() -> "prometheus".
 roots() -> ["prometheus"].
 
 fields("prometheus") ->
-    [ {push_gateway_server, sc(string(), #{default => "http://127.0.0.1:9091", required => true})}
-    , {interval, sc(emqx_schema:duration_ms(), #{default => "15s", required => true})}
-    , {enable, sc(boolean(), #{default => false, required => true})}
+    [ {push_gateway_server, sc(string(),
+                               #{ default => "http://127.0.0.1:9091"
+                                , required => true
+                                , desc => "URL of Prometheus pushgateway."
+                                })}
+    , {interval, sc(emqx_schema:duration_ms(),
+                    #{ default => "15s"
+                     , required => true
+                     , desc => "Data reporting interval in milliseconds."
+                     })}
+    , {enable, sc(boolean(),
+                  #{ default => false
+                   , required => true
+                   , desc => "Enable reporting of metrics via Prometheus Pushgateway."
+                   })}
     ].
 
 sc(Type, Meta) -> hoconsc:mk(Type, Meta).
diff --git a/apps/emqx_statsd/src/emqx_statsd_schema.erl b/apps/emqx_statsd/src/emqx_statsd_schema.erl
index 09522870d..0d6eea3fc 100644
--- a/apps/emqx_statsd/src/emqx_statsd_schema.erl
+++ b/apps/emqx_statsd/src/emqx_statsd_schema.erl
@@ -33,21 +33,33 @@ namespace() -> "statsd".
 roots() -> ["statsd"].
 
 fields("statsd") ->
-    [ {enable, hoconsc:mk(boolean(), #{default => false, required => true})}
+    [ {enable, hoconsc:mk(boolean(),
+                          #{ default => false
+                           , required => true
+                           , desc => "Enable statsd"
+                           })}
     , {server, fun server/1}
-    , {sample_time_interval, fun duration_ms/1}
-    , {flush_time_interval, fun duration_ms/1}
+    , {sample_time_interval, fun sample_interval/1}
+    , {flush_time_interval, fun flush_interval/1}
     ].
 
 server(type) -> emqx_schema:ip_port();
 server(required) -> true;
 server(default) -> "127.0.0.1:8125";
+server(desc) -> "URL of the statsd gateway.";
 server(_) -> undefined.
 
-duration_ms(type) -> emqx_schema:duration_ms();
-duration_ms(required) -> true;
-duration_ms(default) -> "10s";
-duration_ms(_) -> undefined.
+sample_interval(type) -> emqx_schema:duration_ms();
+sample_interval(required) -> true;
+sample_interval(default) -> "10s";
+sample_interval(desc) -> "Data collection interval in milliseconds.";
+sample_interval(_) -> undefined.
+
+flush_interval(type) -> emqx_schema:duration_ms();
+flush_interval(required) -> true;
+flush_interval(default) -> "10s";
+flush_interval(desc) -> "Flush interval in milliseconds.";
+flush_interval(_) -> undefined.
 
 to_ip_port(Str) ->
      case string:tokens(Str, ":") of