Should Firebelly have the fire descriptor?

[Tavnazian]

It doesn't, but it does fire damage and grants fire resistance.

[Firebug]

My guess is that they started with Resist Energy, which also doesn't have any elemental keywords, and added on the extra stuff from there.

The original printing (Shattered Star #2, Curse of the Lady's Light) even has the same duration as Resist Energy at 10 min/level. Which frankly makes it a little strong, since its duration is still only reduced by 1 minute per fire breath. I mean, its still only 1d4 damage per use so not terribly OP.