With the new flag decline reasons in place, we have the ability to give a custom reason. It looks like the length limit on that field is pretty small.
The flag that sparked this question was about reversing serial downvotes and my original message was going to be
Not manually, but there are vote-fraud prevention scripts in place. If your downvotes were from the same user, they will probably be reverted. You will need to run a rep recalc when that happens. Keep an eye on http://programmers.stackexchange.com/reputation.
That was too long, so I shortened it to
Not manually, but there are vote-fraud prevention scripts in place. If your downvotes were from the same user, they will probably be reverted.
That was also too long and the final message was
Not manually, but there are vote-fraud prevention scripts in place.
What's the maximum length of a message we can leave? Can there be an error message or a character counter or a physical limit on the length of the field to make the limit more apparent? Can the limit be increased to make the messages more meaningful?
This is the kind of flag where not responding is at best rude, leaving a comment is potentially revealing private information, and it's not dire enough for a private message, so the decline reason in the flags seems like the best way to go.
Edit: the more I think about this, the more it seems to me that this is also an argument for allowing to mark a flag "helpful" and leave a message with it. Docking someone 10 points on their flag weight for contacting a moderator with a legit concern feels wrong.