I seems to be working, but despite changing the values for the bind and client addresses, as well as the client name, the uptime, number of CPUs, and memory usage appear to be the same as the CentOS6.8 server after starting the monitors on the debian8.3 system.
# pmm-admin add mysql --user root --password xxxxxxxxxxxxxxxx --disable-tablestats-limit 10000
[linux:metrics] OK, now monitoring this system.
[mysql:metrics] OK, now monitoring MySQL metrics using DSN root:***@unix(/var/run/mysqld/mysqld.sock)
[mysql:queries] OK, now monitoring MySQL queries from slowlog using DSN root:***@unix(/var/run/mysqld/mysqld.sock)