Should I buy a 7-day pass?

Hello,

My family is planning a ten-day trip in December. I would like to check with you if a JR pass is worth it:

Day 1: Arriving Narita Airport, Tokyo and going to Osaka from there

Day 4: Osaka - Koyasan

Day 5: Koyasan - Kyoto

Day 7: Kyoto - Tokyo

Day 10: Depart Tokyo

For the last 3 days in Tokyo before we depart, what is the best option for us if we intend to travel around Tokyo?

Thank you very much for your help.