  Following Babai's algorithm for the string isomorphism problem, we determine
that it is possible to write expressions of short length describing certain
permutation cosets, including all permutation subgroups; this is feasible both
in the original version of the algorithm and in its CFSG-free version,
partially done by Babai and completed by Pyber. The existence of such
descriptions gives a weak form of the Cameron-Mar\'oti classification even
without assuming CFSG. We also thoroughly explicate Babai's recursion process
(as given in Helfgott) and obtain explicit constants for the runtime of the
algorithm, both with and without the use of CFSG.
