Indoor mint and sage – leaves turning black

My mint growing by the window in my sunroom (facing west) started having leaves turning black (looked burnt and dry like charcoal) on the tip. I tried watering more but it didn’t seem to change.  Actually, something similar is happening…

Cutting back tarragon in fall?

I planted tarragon this year. it did very well. Now it is no longer growing but is a bit of a bushy mess, with straggly stems and large woody stems as well.  Should I cut it back now? If so…