I always use apt-cache as it also searches on description:
$ apt-cache search tacacs
libauthen-tacacsplus-perl - Perl module for authentication using
TACACS+ server
libpam-tacplus - PAM module for using TACACS+ as an authentication
service
strange .... in my search, the system find only one Package
# apt-cache search tacacs
libauthen-tacacsplus-perl - Perl module for authentication using
TACACS+ server
#
# cat /etc/apt/sources.list
deb http://deb.debian.org/debian bullseye main
deb-src http://deb.debian.org/debian bullseye main
deb http://deb.debian.org/debian-security/ bullseye-security main
deb-src http://deb.debian.org/debian-security/ bullseye-security main
deb http://deb.debian.org/debian bullseye-updates main
deb-src http://deb.debian.org/debian bullseye-updates main
#
Bullseye 11.2