diff --git a/src/main/java/eu/dnetlib/validator2/engine/Reporter.java b/src/main/java/eu/dnetlib/validator2/engine/Reporter.java
index 0760559..f62d335 100644
--- a/src/main/java/eu/dnetlib/validator2/engine/Reporter.java
+++ b/src/main/java/eu/dnetlib/validator2/engine/Reporter.java
@@ -36,4 +36,11 @@ public class Reporter<T, R extends Rule<T>> {
             logger.error("Failed to report error of applying " + rule + " to value: " + t, throwable);
         }
     }
+
+    @Override
+    public String toString() {
+        return "Reporter{" +
+                "diagnostics=" + diagnostics +
+                '}';
+    }
 }
diff --git a/src/main/java/eu/dnetlib/validator2/validation/guideline/GuidelineEvaluation.java b/src/main/java/eu/dnetlib/validator2/validation/guideline/GuidelineEvaluation.java
index 6622e8b..902e188 100644
--- a/src/main/java/eu/dnetlib/validator2/validation/guideline/GuidelineEvaluation.java
+++ b/src/main/java/eu/dnetlib/validator2/validation/guideline/GuidelineEvaluation.java
@@ -135,6 +135,21 @@ class GuidelineEvaluation {
         return ruleIdToRequirementLevel.get(ruleId);
     }
 
+    @Override
+    public String toString() {
+        return "GuidelineEvaluation{" +
+                "subjectId='" + subjectId + '\'' +
+                ", doc=" + doc +
+                ", weight=" + weight +
+                ", warnings=" + warnings +
+                ", errors=" + errors +
+                ", ruleIdToRequirementLevel=" + ruleIdToRequirementLevel +
+                ", ruleIdToNodeList=" + ruleIdToNodeList +
+                ", diagnostics=" + diagnostics +
+                ", reporter=" + reporter +
+                '}';
+    }
+
 
     private static final class Diagnostics extends StandardRuleDiagnostics<Document, SyntheticRule<Document>> {
 
@@ -164,5 +179,12 @@ class GuidelineEvaluation {
         private Status statusFor(String ruleId) {
             return statusByRuleId.get(ruleId);
         }
+
+        @Override
+        public String toString() {
+            return "Diagnostics{" +
+                    "statusByRuleId=" + statusByRuleId +
+                    '}';
+        }
     }
 }