CA Support does not recommend allowing direct access to the MDB from third-party applications. Depending on how much of a load that third-party applications put on the database, it may hurt the performance of Service Desk. Depending on how the access is given to third-party tools, it is not possible to guarantee if it can hurt the integrity of the MDB.
What CA Support recommends is to set up the offline reporting instance of Service Desk (using transaction replication) and run third-party applications against that instead of the production MDB.
Any access from third-party applications must be read-only even when accessing the offline reporting instance.