<prompt> Translate the following text to SwahiliHowever, cost models have significant limitations in accuracy unless their underlying assumptions of system size and cost drivers are carefully chosen and reflect the agencys previous experience in system development.  <response>: Hata hivyo, mifano ya gharama zina mapungufu makubwa katika usahihi isipokuwa dhana zao za msingi za ukubwa wa mfumo na madereva ya gharama huchaguliwa kwa uangalifu na kutafakari uzoefu wa zamani wa shirika katika maendeleo ya mfumo. 