Whatever the speaker chooses as the independent, principal and absolute source of action is called kartā or agent.,
The agent is absolute and unconditioned, as, देवदत्तः पचति Devadatta cooks. स्थाली पचति the pot cooks.,
स्वतन्त्रः कर्ता
Adhyāya 1 · Pāda 4 · Rule 54