Best practice to prevent lack of tools?

The only way to reduce consumption of tools is to upgrade to steel tools, which last twice as long as iron ones. Besides that, the only thing you can do to avoid a tool shortage is to

1. Increase the limit for the blacksmith if he/she is consistently hitting their limit
2. If not, make sure your blacksmith is productive by ensuring he/she doesn't have too far to walk
3. Build more blacksmiths
4. Always make sure you have enough iron and logs (and coal, if you go for the steel option).

A tool crisis is a serious problem which can be the downfall of your village. Lack of tools greatly affects the productivity of almost all jobs, including blacksmiths, which in turn reduces the tool production even more and makes it hard to get out of. To make matters worse, a tool crisis will often be followed by a hunger-crisis and mass-starvation, because the productivity of all food-sources is also affected. Good luck increasing your tool production while your blacksmiths and builders are dying one after another.

That means a tool bottleneck needs to be prevented at all cost. Make sure that you always have at least one replacement tool stocked per adult citizen, better two. When your number of citizens exceeds the number of tools you have stocked, you need to act quickly and build more blacksmith workshops.

Also, make sure that your blacksmiths never run into a supply bottleneck. To prevent this from happening, get a forestry and a mine for a constant source of logs and iron. That way you no longer need to harvest iron and logs manually. When you have the manpower available, you should get a second mine to produce coal, so you can produce steel tools.