feeding eggs

 Both.  It's slightly different depending on what you feed, but either one supplies far more Phosphorus, by itself, than calcium.  Basically any boneless animal protein source will provide phosphorus without a balance of calcium.

Many premium kibbles have a slightly higher calcium level than strictly ideal so that allows for the addition of goodies.  So you can throw in an egg or two per week with no problem, or cottage/ricotta cheese, or a smidge of meat, or whatever.  If you go over 25% of the total diet you do have to figure out the phosphorus/calcium ratio at the very least.

 Eggs are fine! I give them to my dog on an average of once a week, shells and all.

Jewlieee

 I just hand the entire egg to my dogs, shell and all. Then they run off to their spot in the yard and eat them up.

I tried that with Caleb, and he took the egg into the living room to play with.  Now I crack the egg into his dish with his breakfast, and toss the shell on top.