• The returned expression should not have unecessary 0 or 1 factors. For example it should not return (* 1 (+ x 1)) but simply the term (+ x 1) similarly it should not return (* 0 (+ x 1)) instead it should return just 0
• Results with two constant values such as for example (+ 2 2) should be evaluated and returned as a single value 4
• Any argument raised to the zero power should return 1 and if raised to 1 should return the same value or variable. For example (^ x 0) should return 1 and (^ x 1) should return x
• No simplifactions are expected for functions like cos, sin, exp, ln... (but their arguments might require a simplification).

No more, no less.

Already raised below.

Still can't sense what depth of simplification and derivation is expected.

For example, shall it simplify expressions like (1-x^2) / (1+x)^2 or more complicated polynomial expressions?

Or shall the code derive functions like (ax)^(bx)^(cx)?