diff --git a/ortools/sat/python/cp_model.py b/ortools/sat/python/cp_model.py
index be6f2282b3..27513448c8 100644
--- a/ortools/sat/python/cp_model.py
+++ b/ortools/sat/python/cp_model.py
@@ -2205,7 +2205,19 @@ def add_abs_equality(self, target: LinearExprT, expr: LinearExprT) -> Constraint
     def add_modulo_equality(
         self, target: LinearExprT, expr: LinearExprT, mod: LinearExprT
     ) -> Constraint:
-        """Adds `target = expr % mod`."""
+        """Adds `target = expr % mod.
+
+        It uses the C convention, that is the result is the remainder of the
+        integral divisiion rounded towards 0.
+        
+        Args:
+        target: the target expression.
+        expr: the expression to compute the modulo of.
+        mod: the modulus expression.
+        
+        Returns:
+        A `Constraint` object.
+        """
         ct = Constraint(self)
         model_ct = self.__model.constraints[ct.index]
         model_ct.int_mod.exprs.append(self.parse_linear_expression(expr))