I think your current mantle is too thin, short and dark.

I replaced it w/something like this

I put a throw in the basket for some more texture. take away the other flower pot next to the tools.

in the season where you aren't using the tools, remove it, replace w/something like this.

this is one of my favorites, but only if you have something interesting to reflect

I like this too. this mantle is similar to yours but it goes all the way across. try copying what they've done here, only not as much (yours is a smaller length)

gave you logs in the basket.

btw, have you thought about doing a charcoal color on the walls (the top two here match great w/your mortar on the FP) they are grays that have yellow undertones, so they'd work perfectly w/the stones.