You use tower reported wind
That certainly would not be advisable in certain parts of the world (like many airfields in Africa for instance.
The worst case I have experienced was a tower report of calm with wind on the ND indicating 28 kts tailwind at 200 RA - the runway was wet.
Use all available sources to determine the actual wind conditions. If in doubt err on the side of safety, and certainly do not blindly follow tower reports.