In:
https://cloud.ibm.com/docs/api-handbook?topic=api-handbook-errors
I cannot quite reconcile:
'message | String | This field MUST contain a plainly-written, developer-oriented explanation of the solution to the problem in complete, well-formed sentences.'
with:
'message values SHOULD describe the problem and MAY also provide suggestions or solutions.'
More specifically, it sounds to me that 'MAY also provide [...] solutions' is not compatible with 'MUST contain [an] explanation of the solution'.
The MAY requirement is repeated lower in the topic.