The human developer would just write what the code does, because the commit also contains an email address that identifies who wrote the commit. There's no reason to write:

> Commit f9205ab3 by dkenyser on 2026-3-31 at 16:05:

> Fixed the foobar bug by adding a baz flag - dkenyser

Because it already identified you in the commit description. The reason to add a signature to the message is that someone (or something) that isn't you is using your account, which seems like a bad idea.

Aside from merges that combine commits from many authors onto a production branch or release tag. I would personally not leave an agent to do that sort of work.