Full Idea
Getting from a Tarskian definition of truth to a substantive account of the semantic properties of the object language may involve as little as the reintroduction of a primitive notion of truth.
Gist of Idea
We can get a substantive account of Tarski's truth by adding primitive 'true' to the object language
Source
John Etchemendy (Tarski on Truth and Logical Consequence [1988], p.60), quoted by Donald Davidson - Truth and Predication 1
Book Reference
Davidson,Donald: 'Truth and Predication' [Belknap Harvard 2005], p.24
A Reaction
This is, I think, the first stage in modern developments of axiomatic truth theories. The first problem would be to make sure you haven't reintroduced the Liar Paradox. You need axioms to give behaviour to the 'true' predicate.