> Is it OK to put Field descriptions directly in:
> RDB$Relation_Fields.RDB$Description?

Yes.

> Can it be done using DSQL tab of WISQL? (it's a blob)
>
> Or is there a better way to put descriptions on fields?

No.

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Server.
Upscene Productions
http://www.upscene.com