You want to permit a command to be run via sudo, but only without command-line arguments.
Follow the program name with the single argument "" in /etc/sudoers:
/etc/sudoers: smith ALL = (root) /usr/local/bin/mycommand "" smith$ sudo -u root mycommand a b c Rejected smith$ sudo -u root mycommand Authorized
If you specify no arguments to a command in /etc/sudoers, then by default any arguments are permitted.
/etc/sudoers: smith ALL = (root) /usr/local/bin/mycommand smith$ sudo -u root mycommand a b c Authorized
Use "" to prevent any runtime arguments from being authorized.
sudo(8), sudoers(5).