Use :returns:

rclpy/rclpy/client.py

@@ -88,7 +88,8 @@ def wait_for_service(self, timeout_sec=None):
 
         :param timeout_sec: Seconds to wait. Block forever if None or negative. Don't wait if 0
         :type timeout_sec: float or None
-        :rtype: bool true if the service is available
+        :rtype: bool
+        :returns: true if the service is available
         """
         timeout_nsec = rclpy.utilities.timeout_sec_to_nsec(timeout_sec)
         result = self.service_is_ready()

rclpy/rclpy/executors.py

@@ -49,7 +49,8 @@ def wait(self, timeout_sec=None):
 
         :param timeout_sec: Seconds to wait. Block forever if None or negative. Don't wait if 0
         :type timeout_sec: float or None
-        :rtype: bool True if all work completed
+        :rtype: bool
+        :returns: True if all work completed
         """
         if timeout_sec is not None and timeout_sec < 0:
             timeout_sec = None

rclpy/rclpy/graph_listener.py

@@ -63,7 +63,7 @@ def add_timer(self, timer_period_ns, callback):
         :type timer_period_ns: integer
         :param callback: called when the graph updates
         :type callback: callable
-        :rtype: rclpy.timer.WallTimer instance
+        :rtype: rclpy.timer.WallTimer
         """
         with self._lock:
             tmr = _WallTimer(callback, None, timer_period_ns)

rclpy/rclpy/utilities.py

@@ -47,6 +47,11 @@ def timeout_sec_to_nsec(timeout_sec):
 
     Python tends to use floating point numbers in seconds for timeouts. This utility converts a
     python-style timeout to an integer in nanoseconds that can be used by rcl_wait.
+
+    :param timeout_sec: Seconds to wait. Block forever if None or negative. Don't wait if 0
+    :type timeout_sec: float or None
+    :rtype: int
+    :returns: rcl_wait compatible timeout in nanoseconds
     """
     if timeout_sec is None:
         # Block forever