I think the most important thing is that the commit message should capture the high level intent of the change. I write "intent", because the actual effect and

I think the most important thing is that the commit message should capture the high level intent of the change. I write "intent", because the actual effect and "intent" can differ, and commit messages are immutable. It's fine, as long as you recognize that the commit message is there to capture original intent. You often see "Fix bug #1234", but you rarely see "Introduce bug #1234". The other stuff about using consistent tense, capitalization, punctuation, etc... is important, but secondary.