The allegation of the anti Ahmadis is that if Ahmadas was the mujadid why did he need to claim it. Certainly other mujadids must have also made this claim if it was necessary while no mujadid has. This is another false allegation.
It is narrated by Imam Suyutirh that Hadhrat Umar Ibn Abd Al Azizrh claimed to be the mujadid of the age (Tarikh al Khulafa)
It was also stated that Imam Ahmad Ibn Hanbalrh stated that Hadhrat Umar Ibn Abd Al Azizrh was the mujadid of the first century of hijra while Imam Shafirh was the mujadid of the second century (Hanbal, Imam Abu Abd Allah Ahmad, Aun Al Ma’bud, Sharh Abu Dawood Volume 4 page 148)
Hadhrat Shah Wali Ullah Dehlvirh claimed to be honored with the robe of a reformer (Shah, Sayyid Wali Ullah, Tafhimat Ilahiyya)
Hadhrat Sayyid Ahmad Shah Barelvirh claimed the leadership of the Muslim ummah in the capacity of a mujadid (Barelvi, Ahmad Shah, Swanih Ahmadi page 245)
Hadhrat Sheikh Ahmadrh of Sirhind who is known as Mujadid Al Thani because of his claim to be the Mujadid (Sirhind, Sheikh Ahmad, Maktubat Volume 2 Letter 4)
Hadhrat Imam Ghazalirh explained how he had attained the status and how he became the mujadid of his age (Ghazali, Imam, Al Munqidh min al Dalal)
Hadhrat Imam Taymiyyahrh referred to himself as the mujadid of his age as well while Imam Suyutirh hoped to be the mujadid of the age (Imam Suyuti, Hujuj al Kiramah, Page 138)
It is clear that there is nothing wrong with the claim of being a mujadid and many have done it in the past. It is also true that when the Messiah was to arrive he would be the mujadid and therefore it is obvious that he would have to announce it as well.