Re-introduce DESCRIBE permission

We have a cluster like this:

project1_keyspace
table101
table102

project2_keyspace
table201
table202

We have set up following users and grants:

project1_user has all access to project1_keyspace
project2_user has all access to project2_keyspace

However project1_user can still do a 'describe schema' and get the schema for project2_keyspace as well. We do not want project1_user to have any knowledge for project2 in any way (cqlsh/java-driver etc) .