diff --git a/src/main/java/org/apache/commons/math4/ml/clustering/ClusterEvaluator.java b/src/main/java/org/apache/commons/math4/ml/clustering/ClusterEvaluator.java
index ce50bdfed..e15dd1e8d 100644
--- a/src/main/java/org/apache/commons/math4/ml/clustering/ClusterEvaluator.java
+++ b/src/main/java/org/apache/commons/math4/ml/clustering/ClusterEvaluator.java
@@ -19,6 +19,9 @@ package org.apache.commons.math4.ml.clustering;
 
 import java.util.List;
 
+/**
+ * Defines a measure of the quality of clusters.
+ */
 public interface ClusterEvaluator {
     /**
      * @param cList List of clusters.
@@ -27,6 +30,8 @@ public interface ClusterEvaluator {
     double score(List<? extends Cluster<? extends Clusterable>> cList);
 
     /**
+     * Provides a means to interpret the {@link #score(List) score value}.
+     *
      * @param a Score computed by this evaluator.
      * @param b Score computed by this evaluator.
      * @return {@code true} if the evaluator considers that score