Set IAM Role Description
Seems like it has been added as of September 3rd, 2019. Check this part of the AWS CloudFormation docs.
Update November 2019:
The Description
field is now supported in CloudFormation.
Properties:
AssumeRolePolicyDocument: Json
Description: String <--- Here
ManagedPolicyArns:
- String
MaxSessionDuration: Integer
Path: String
PermissionsBoundary: String
Policies:
- Policy
RoleName: String
Tags:
- Tag
Tested and can confirm John Rotenstein's answer remains the best option as of 29/Mar/2019. Sometimes updates can sneak in without making the documentation, but not in this case unfortunately.
(Would have preferred to put this as a comment however the reputation requirement is a pain)
Edit: July/2019 - Still no update, however this can be done through the SDK