diff --git a/puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_send_receive_time b/puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_send_receive_time
index 3514a5a054..19a67bec36 100755
--- a/puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_send_receive_time
+++ b/puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_send_receive_time
@@ -25,7 +25,10 @@ import scripts.lib.setup_path_on_import
 
 import django
 
+from typing import Any, Dict, List, Optional
+
 def total_seconds(timedelta):
+    # type: (datetime.timedelta) -> float
     return (timedelta.microseconds + (timedelta.seconds + timedelta.days * 24 * 3600) * 10**6) / 10.**6
 
 usage = """Usage: send-receive.py [options] [config]
@@ -90,6 +93,7 @@ states = {
     }
 
 def report(state, timestamp, msg=None):
+    # type: (str, Any, Optional[str]) -> None
     now = int(time.time())
     if msg is None:
         msg = "send time was %s" % (timestamp,)
@@ -101,11 +105,13 @@ def report(state, timestamp, msg=None):
     exit(states[state])
 
 def send_zulip(sender, message):
+    # type: (zulip.Client, Dict[str, Any]) -> None
     result = sender.send_message(message)
     if result["result"] != "success" and options.nagios:
         report("CRITICAL", "Error sending Zulip, args were: %s, %s" % (message, result))
 
 def get_zulips():
+    # type: () -> List[Dict[str, Any]]
     global queue_id, last_event_id
     res = zulip_recipient.get_events(queue_id=queue_id, last_event_id=last_event_id)
     if 'error' in res.get('result'):
diff --git a/puppet/zulip/files/nagios_plugins/zulip_nagios_server/check_postgres_replication_lag b/puppet/zulip/files/nagios_plugins/zulip_nagios_server/check_postgres_replication_lag
index 2e56f00e84..3ebb62c8dc 100755
--- a/puppet/zulip/files/nagios_plugins/zulip_nagios_server/check_postgres_replication_lag
+++ b/puppet/zulip/files/nagios_plugins/zulip_nagios_server/check_postgres_replication_lag
@@ -17,10 +17,12 @@ states = {
     }
 
 def report(state, msg):
+    # type: (str, str) -> None
     print("%s: %s" % (state, msg))
     exit(states[state])
 
 def get_loc_over_ssh(host, func):
+    # type: (str, str) -> str
     try:
         return subprocess.check_output(['ssh', host,
                                         'psql zulip -t -c "SELECT %s()"' % (func,)],
@@ -30,6 +32,7 @@ def get_loc_over_ssh(host, func):
         report('CRITICAL', 'ssh failed: %s: %s' % (str(e), e.output))
 
 def loc_to_abs_offset(loc_str):
+    # type: (str) -> int
     m = re.match(r'^\s*([0-9a-fA-F]+)/([0-9a-fA-F]+)\s*$', loc_str)
     if not m:
         raise ValueError("Unknown xlog location format: " + loc_str)
diff --git a/puppet/zulip/files/nagios_plugins/zulip_postgres_appdb/check_fts_update_log b/puppet/zulip/files/nagios_plugins/zulip_postgres_appdb/check_fts_update_log
index 205e239a67..6f9b39d756 100755
--- a/puppet/zulip/files/nagios_plugins/zulip_postgres_appdb/check_fts_update_log
+++ b/puppet/zulip/files/nagios_plugins/zulip_postgres_appdb/check_fts_update_log
@@ -22,6 +22,7 @@ states = {
     }
 
 def report(state, num):
+    # type: (str, str) -> None
     print("%s: %s rows in fts_update_log table" % (state, num))
     exit(states[state])
 
diff --git a/puppet/zulip/files/nagios_plugins/zulip_postgres_common/check_postgres_backup b/puppet/zulip/files/nagios_plugins/zulip_postgres_common/check_postgres_backup
index 63c5c0e34d..1e85030f54 100755
--- a/puppet/zulip/files/nagios_plugins/zulip_postgres_common/check_postgres_backup
+++ b/puppet/zulip/files/nagios_plugins/zulip_postgres_common/check_postgres_backup
@@ -16,6 +16,7 @@ states = {
     }
 
 def report(state, msg):
+    # type: (str, str) -> None
     print("%s: %s" % (state, msg))
     exit(states[state])