diff --git a/mbtrack2/tracking/rf.py b/mbtrack2/tracking/rf.py
index 4de4aa28530c1f3942fa81d47a11f2fb19670ffa..62a2798defffd5036a880e91595b83c98ff50d56 100644
--- a/mbtrack2/tracking/rf.py
+++ b/mbtrack2/tracking/rf.py
@@ -171,6 +171,8 @@ class CavityResonator():
         Plot phasor diagram.
     is_DC_Robinson_stable(I0)
         Check DC Robinson stability.
+    is_CBI_stable(I0)
+        Check Coupled-Bunch-Instability stability.
     plot_DC_Robinson_stability()
         Plot DC Robinson stability limit.
     init_tracking(beam)
@@ -950,7 +952,7 @@ class CavityResonator():
                       modes=None,
                       bool_return=False):
         """
-        Check Coupled-Bunch-Instability stability,
+        Check Coupled-Bunch-Instability stability.
         Effect of Direct RF feedback is not included.
 
         This method is a wraper around lcbi_growth_rate to caluclate the CBI
@@ -1003,9 +1005,9 @@ class CavityResonator():
 
         if bool_return:
             if growth_rate > 1 / self.ring.tau[2]:
-                return True
-            else:
                 return False
+            else:
+                return True
         else:
             return growth_rate, mu