descseq allows you to change the name or description of a sequence, then write out a new file containing the changes. The original sequence is unaltered.
Set the name of a sequence to "myclone23":
% descseq -seq clone23 -out clone23.seq -name "myclone23"
Set the description of a sequence to "This is my clone number 244":
% descseq -seq xy24 -out xy24.seq -desc "This is my clone number 244"
Append some text to the description of a sequence:
% descseq -seq est.seq -out est4.seq -desc " (submitted)" -append