Abraham (around 1800 BC) performed circumcision. At that period, what tool must he have used to do that?
Also, Genesis 18:7-8 says he cooked a calf. What tool must he have used to kill the calf at such an old time?
The description of Abraham's circumcision in the Bible doesn't say what tool he used. However, Joshua is described as having circumcised the Israelites with swords of stone (Joshua 5:2), and, as רבות מחשבות notes, Zipporah also used a rock to circumcise her son (Exodus 4:25), so Abraham probably used something similar.
The text also doesn't describe what tool he used to kill the calf, but in the description of the binding of Isaac, he brought a knife (Genesis 22:10), so that is probably what he used for slaughtering.