Why ? Is there something i've missed in the ability description ?
Because as far as i know, except for Second Sight, who clearly state it's not required, i haven't seen any precision about that.
And Comprehend Magic, the "more advanced kind of sensitivity" for example, need to penetrate.
I would agree it doesn't need to, because if so i would found the ability really difficult to use for that purpose, but i really haven't seen anything clear about it.
Ah, careful there. Comprehend Magic doesn't need to penetrate for determining the presence of magic, just for the subsequent information, which is generally beyond the scope of Magic Sensitivity.
Although determining the presence of magic requires but a moment of observation, the character must maintain concentration (ArM5, page 82) to acquire any of the subsequent information. If observing a being with Magic Resistance, this power must penetrate, as usual; but even if the Penetration Total proves to be insufficient, the character is aware of the presence of magic if the Ease Factor was met.
Indeed, this is actually part of why I say so definitively that Magic Sensitivity doesn't need to penetrate.
I totally agree, for me too, Sensibility shoudn't need to penetrate.
But i've seen debate about this topic and it's not as clear as it seems. And as i agree Comprehend Magic suggest this for Sensibility, I must say it's a little confusing and you need to know Comprehend Magic to understand it doesn't need to penetrate.
It's a perfectly good rule for play. My point is that the description in the rule book says what you can do with the ability, and it doesn't mention "detect the Gift", or give a target number for doing that. That's a gap in the description (given it does appear that it should be possible).