describe: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/cmtk/bin/describe - from package: cmtk

You may install the required package with command apt-get install {package}
Error in other languages:
describe: bevel nie gevind nie
describe: comandă negăsită
describe: comando não encontrado
describe: commande introuvable
describe: command not found
describe: käsku ei ole
describe: không tìm thấy lệnh
describe: komanda nerasta
describe: Kommando nicht gefunden.
describe: kommandot finns inte
describe: komut yok
describe: nie znaleziono polecenia
describe: níor aimsíodh an t-ordú
describe: no se encontró la orden
describe: no s'ha trobat l'ordre
describe: opdracht niet gevonden
describe: parancs nem található
describe: perintah tidak ditemukan
describe: príkaz nenájdený
describe: příkaz nenalezen
describe: команда не найдена
describe: командата не е открита
describe: 命令找不到
describe: コマンドが見つかりません