I will start applying for jobs soon, but my experience will have a recent 3 month long work in a single company (which from what I have learned, is a general bad impression).

Should I preemptively explain in my cover letter the reason for having such a record? Or should I wait for them to ask? Or is it better to straight up include it in the resume that it is a contractual job?

If I don't, would it hurt my chances? In other words, would some employers immediately not consider a resume which has a history of short employment times?