diff --git a/packages/@aws-cdk/aws-iam/lib/policy-document.ts b/packages/@aws-cdk/aws-iam/lib/policy-document.ts
index 9d73acb4693ac..770ab4e9556a0 100644
--- a/packages/@aws-cdk/aws-iam/lib/policy-document.ts
+++ b/packages/@aws-cdk/aws-iam/lib/policy-document.ts
@@ -128,6 +128,8 @@ export class PolicyDocument implements cdk.IResolvable {
    * requirements for any policy.
    *
    * @see https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html#access_policies-json
+   *
+   * @returns An array of validation error messages, or an empty array if the document is valid.
    */
   public validateForAnyPolicy(): string[] {
     const errors = new Array<string>();
@@ -142,6 +144,8 @@ export class PolicyDocument implements cdk.IResolvable {
    * requirements for a resource-based policy.
    *
    * @see https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html#access_policies-json
+   *
+   * @returns An array of validation error messages, or an empty array if the document is valid.
    */
   public validateForResourcePolicy(): string[] {
     const errors = new Array<string>();
@@ -156,6 +160,8 @@ export class PolicyDocument implements cdk.IResolvable {
    * requirements for an identity-based policy.
    *
    * @see https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html#access_policies-json
+   *
+   * @returns An array of validation error messages, or an empty array if the document is valid.
    */
   public validateForIdentityPolicy(): string[] {
     const errors = new Array<string>();
diff --git a/packages/@aws-cdk/aws-iam/lib/policy-statement.ts b/packages/@aws-cdk/aws-iam/lib/policy-statement.ts
index 688cf39faea18..200592f69c6e5 100644
--- a/packages/@aws-cdk/aws-iam/lib/policy-statement.ts
+++ b/packages/@aws-cdk/aws-iam/lib/policy-statement.ts
@@ -442,6 +442,8 @@ export class PolicyStatement {
 
   /**
    * Validate that the policy statement satisfies base requirements for a policy.
+   *
+   * @returns An array of validation error messages, or an empty array if the statement is valid.
    */
   public validateForAnyPolicy(): string[] {
     const errors = new Array<string>();
@@ -453,6 +455,8 @@ export class PolicyStatement {
 
   /**
    * Validate that the policy statement satisfies all requirements for a resource-based policy.
+   *
+   * @returns An array of validation error messages, or an empty array if the statement is valid.
    */
   public validateForResourcePolicy(): string[] {
     const errors = this.validateForAnyPolicy();
@@ -464,6 +468,8 @@ export class PolicyStatement {
 
   /**
    * Validate that the policy statement satisfies all requirements for an identity-based policy.
+   *
+   * @returns An array of validation error messages, or an empty array if the statement is valid.
    */
   public validateForIdentityPolicy(): string[] {
     const errors = this.validateForAnyPolicy();