You have the ability to cast spells in with variety of magic that can reproduce the effect of non-Tinker powers. While your Shard provides you with a basic library of spells in each system and an intuitive knowledge of them, you will have to research and invent more powerful spells. Your spells will not be stronger than what Eidolon could do in his prime.
You have a pool of energy to cast spells, you have enough to cast your most powerful spells a dozen times in a short time span. The pool takes 30 minutes to fully recharge. Permanent spells like summons, buffs, and auras reserve part of your reserve while they are active and release the energy when they are canceled or expire.