Certain traditions are so odd or unusual that to use them is to announce your presence to all other magically sensitive creatures in the area.
In general, a creature can sense your use of Sorcery if you are within its Magic squared meters. Someone with Powers or Sorcery can use their skill value instead of their Magic to determine this range. A sorcerer with Divination can sense magic use at even greater ranges, as appropriate for the plot; this can be even over interstellar distances.
Using Magic points worsens this limitation, making your sorcery even more noticeable.