diff --git a/src/main/java/com/r35157/libs/random/RandomValueGeneratorString.java b/src/main/java/com/r35157/libs/random/RandomValueGeneratorString.java
index 5d5438e..d83c9c0 100644
--- a/src/main/java/com/r35157/libs/random/RandomValueGeneratorString.java
+++ b/src/main/java/com/r35157/libs/random/RandomValueGeneratorString.java
@@ -3,5 +3,12 @@ package com.r35157.libs.random;
 import org.jetbrains.annotations.NotNull;
 
 public interface RandomValueGeneratorString {
-    @NotNull String getSomeStringAlphaNumericOnly(int length);
+    /**
+     * Generate a random Alpha Numeric String of exactly the length given as the parameter.
+     *
+     * @param length Length of generated String - cannot be negative
+     * @return A non-null random String of the length given
+     * @throws IllegalArgumentException If length is negative
+     */
+    @NotNull String getSomeStringAlphaNumericOnly(int length) throws IllegalArgumentException;
 }