system
Given the following post, respond as if you're commenting on Reddit:
human
How do you tell the difference between a prehistorical tool's usage date and material date?

Carbon dating and other chemical dating shows us the age of the material but how exactly do we know when something was used or altered?

EDIT: Comments basically say that organic material acts differently to inorganic material and therefore can be chemically dated more accurately. And it is often the more about the surrounding materials that we knew about prior to finding the tool like food debris. Though often largely educated guesses. 

EDIT: It seems we use far more than just carbon dating to find the creation and usage date. Usage of organic material is usually changed in some way, like burnt wood turning to charcoal, which gives more evidence of dating. Other materials like spear/arrow heads can gives clues based on other known sites.
gpt
Also, depending on how the tool was found, it can be dated by what layer of sediment it's under. If it's buried at the same depth in the same area as bones that can be dated,  then usually the tool will be assumed to be from the same period. Obviously,  not as accurate as carbon dating,  but at least it gives a general idea.