A better choice than Tellsimp(after) is probably tellrat. Note that tellrat
works only on expressions in "rat" form (CRE).
Example:
(%i1) tellrat(u^2+v^2+w^2=1);
2 2 2
(%o1) [w + v + u - 1]
(%i2) matrix([0,-w,v],[w,0,-u],[-v,u,0]);
[ 0 - w v ]
[ ]
(%o2) [ w 0 - u ]
[ ]
[ - v u 0 ]
(%i3) eigenvectors(%o2);
Warning - you are redefining the MACSYMA function EIGENVALUES
Warning - you are redefining the MACSYMA function EIGENVECTORS
%I w - u v u w + %I v