Trye DBDesc at http://www.dbdesc.com/purchase.html?dbdesc
I have my own scripts for MSSQL however there are couple of other flavors of DBs such as FireBird that I did not want to go and learn the system so I could document the DB therefore I used this tool and viola I am done with that.
give it a shot..
good luck
Cheers,
John Esraelo