hsqldb, if started as embedded (or stand-alone in-process) in Openfire, I believe will only allow connections from within the same JVM, not another tool such as “java -jar sqltool.jar”
If you start hsqldb separate (HSQLDB Server Instance), listening on some port, then configure Openfire to connect to it, you should also be able to access it from other tools not running in the same JVM.
The docs and hsqldb.org website seem to be down at the moment.
You might find this useful
See the section titled "In-Process (Standalone) Mode"
This mode runs the database engine as part of your application program in the same Java Virtual Machine. For most applications this mode can be faster, as the data is not converted and sent over the network. The main drawback is that it is not possible by default to connect to the database from outside your application. As a result you cannot check the contents of the database with external tools such as Database Manager while your application is running. In 1.8.0, you can run a server instance in a thread from the same virtual machine as your application and provide external access to your in-process database.
Also see the section "Server Modes"
Server modes provide the maximum accessibility. The database engine runs in a JVM and listens for connections from programs on the same computer or other computers on the network. Several different programs can connect to the server and retrieve or update information. Applications programs (clients) connect to the server using the HSQLDB JDBC driver. In most server modes, the server can serve up to 10 databases that are specified at the time of running the server.