cat $(puppet agent --configprint resourcefile) - List all resources managed by puppet.
cat $(puppet agent --configprint agent_disabled_lockfile) - Check whether the puppet agent is disabled and why.
puppet agent --disable "Who disabled puppet agent, when and why." - Disable the puppet agent.
cat /opt/puppetlabs/puppet/cache/state/classes.txt - List all classes applied to the current node. Note the file location may be configured differently.
puppet agent --test --noop - Run the puppet agent once in noop mode without starting the daemon, to check what would be applied.