diff --git a/mbtrack2/tracking/particles.py b/mbtrack2/tracking/particles.py
index 5b973d14ecb43a02663fde0238d9da86c68d2cd6..395de32462c2d3a0692a8ec2ff88ab9ede3eac81 100644
--- a/mbtrack2/tracking/particles.py
+++ b/mbtrack2/tracking/particles.py
@@ -299,6 +299,9 @@ class Bunch:
         """
         Return the average Courant-Snyder invariant of each plane.
 
+        To get non-zero longitudinal Courant-Snyder invariant, the longitudinal
+        Twiss parameters need to be computed using the ring.get_longitudinal_twiss
+        method.
         """
         Jx = ((self.ring.optics.local_gamma[0] * self["x"]**2) +
               (2 * self.ring.optics.local_alpha[0] * self["x"]) * self["xp"] +
diff --git a/mbtrack2/tracking/synchrotron.py b/mbtrack2/tracking/synchrotron.py
index c357198ac9043086bab53c92ec19d329fe606ee5..e9df8ffe23882de2af3d7631588201c77f9b70bc 100644
--- a/mbtrack2/tracking/synchrotron.py
+++ b/mbtrack2/tracking/synchrotron.py
@@ -459,17 +459,18 @@ class Synchrotron:
             Harmonics of the cavities to consider.
             Default is None.
         add : bool, optional
-            If True, 
-            
+            If True, add the computed longitudinal Twiss parameters as class
+            arguements.
+
         Usage
         -----
-        - If a single voltage value is given, assume a single RF system set at 
+        - If a single voltage value is given, assume a single RF system set at
         the synchronous phase.
-        - If a single pair of voltage/phase value is given, assume a single RF 
+        - If a single pair of voltage/phase value is given, assume a single RF
         system at this setting.
-        - Otherwise, compute the synchrotron tune for a multi-harmonic RF 
+        - Otherwise, compute the synchrotron tune for a multi-harmonic RF
         system.
-            
+
         Returns
         -------
         tuneS : float