tiling on stairs

We are currently building a project home with a company. Prior to commencing we informed them that we would require tiles to the first stair flight of the split level home.
They forgot to do this, and when informed they have subsequently fixed timber to the front face of the riser to bring it in line with the front of the bullnose tread.
They have said that this adequate to tile over, but I am concerned that having a bullnosed edge to the stair may lead to cracking of the nosing tile.
Can anyone advise?? Please.

Get the tiles whacked on ya big jessie.
Only teasing. The tiles should be supported fine by the time you've grouted.