Mentioning some attributes of the engaged couple in order to advise them and make them aware of each other before marriage is not considered Ghibah, which Allah and His Messenger prohibited; rather, this is considered sincerity in one's advice as recommended in the Hadith
Religion is based on advising one another...Etc.
It is also an act of cooperating in righteousness and goodness. Allah (Exalted be He) says:
Help you one another in Al-Birr and At-Taqwâ (virtue, righteousness and piety)
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.