diff --git a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
index 23abcb34d20..33bafc2fbb6 100644
--- a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
+++ b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
@@ -222,7 +222,13 @@ pub enum Instruction {
     /// Binary Operations like +, -, *, /, ==, !=
     Binary(Binary),
 
-    /// Converts `Value` into the given NumericType
+    /// Converts `Value` into the given `NumericType`
+    ///
+    /// This operation only changes the type of the value, it does not change the value itself.
+    /// It is expected that the value can fit into the target type.
+    /// For instance a value of type `u32` casted to `u8` must already fit into 8 bits
+    /// A value of type `i8` cannot be casted to 'i16' since the value would need to include the sign bit (which is the MSB)
+    /// Ssa code-gen must ensure that the necessary truncation or sign extension is performed when emitting a Cast instruction.
     Cast(ValueId, NumericType),
 
     /// Computes a bit wise not