I've noticed in general that the hover-over hints for verbs in future-tense questions aren't correct. Here it seems to read it as "we tell" and gives "insímid" accordingly.
Why is there no "f" in this future tense verb?
Only first conjugation verbs have future suffixes that begin with an F — viz -faimid or -fimid in the synthetic second person plural. Their second conjugation analogues have -óimid or -eoimid instead.
Ok thanks so much!