I'd like to be able to send the details of an alert entirely in the top level text field (so not the one nested under attachements[0]) to Slack without having to use the attachments.

This is probably a backwards steps for most usage but it would allow users to be able to send useful messages to a Slack Workflow webhook. Slack Workflow webhooks are nice in that they can be easily managed by users without admin permissions and shared by users. Their downside is that, as of right now, they are unable to read information out of nested JSON and so it's not possible to read Alertmanager notification details and then output that usefully.

From some testing this doesn't allow you to use any markdown or other formatting so it's very bare bones but still potentially useful for those who are Prometheus admins but not Slack admins.

I'm happy to raise an MR for this you'd accept one.