Attaching policy to Lambda fails using SAM

I'm trying to attach the CloudFormationDescribeStacksPolicy to a Lambda in my SAM template file like so,

  getEnvironment:
    Type: AWS::Serverless::Function
    DependsOn: AppTable
    Properties:
      Handler: src/getEnvironment.handler
      Description: Get environment details
      Policies:
        - DynamoDBCrudPolicy:
            TableName: !Ref AppTable
        - CloudFormationDescribeStacksPolicy
      Events:
        ClientApi:
          Type: Api
          Properties:
            RestApiId: !Ref ClientApi
            Path: /environment
            Method: GET

But the CloudFormation deployment fails with,

CREATE_IN_PROGRESS       AWS::IAM::Role           getEnvironmentRole       ARN CloudFormationDesc 
                                                                           ribeStacksPolicy is    
                                                                           not valid. (Service:   
                                                                           Iam, Status Code: 400, 
                                                                           Request ID:

Any idea what the issue might be here?

According to AWS SAM policy templates documentation (https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-policy-templates.html): "If a policy template does not require any placeholder values, you must specify an empty object"

Try:

  Policies:
        - CloudFormationDescribeStacksPolicy: {}