Hello @nmourad thanks for using the SDK and for raising this.

This method actually exists as you can see from https://github.com/microsoftgraph/msgraph-sdk-python/blob/main/msgraph/generated/security/incidents/item/alerts/item/comments/comments_request_builder.py

mappig to the URL call https://graph.microsoft.com/v1.0/security/incidents/{incident-id}/alerts/{alert-id}/comments

It can be used via a snippet like:

Also Check that your account is provisioned and appropriate permisions are assigned

Hello,
This method exists indeed for alerts linked to an incident but not to directly comment on an Incident that can have n alerts (like i mentioned on my issue report)
Doing what's below I've been able to make it work and put a comment on the incident directly (not on the alerts in the incident) so this method exist at incident level (also mentioned on this doc : https://learn.microsoft.com/en-us/graph/api/security-incident-post-comments?view=graph-rest-1.0&tabs=http

@shemogumbe This is not a discussion, but still an issue, the endpoint still does not exist in the latest version of msgraph-sdk-python.