Final answer:
The primary tool for assessing fetal heart tones is the stethoscope, which is used to auscultate the heart rate as part of the Apgar score assessment in newborns.
Step-by-step explanation:
The primary tool for assessing fetal heart tones is a stethoscope, a simple yet effective device for auscultation. During the assessment of a newborn's health, using the Apgar score, the heart rate is one of the five criteria evaluated, for which a stethoscope is essential. The mnemonic APGAR stands for “Appearance” (skin color), “Pulse” (heart rate), “Grimace” (reflex), “Activity” (muscle tone), and “Respiration,” which are the key aspects assessed soon after birth to determine the newborn's condition. The Apgar score is taken at 1 and 5 minutes after the birth, and a higher score indicates a smooth transition from the womb, while a lower score may suggest fetal distress.