How to make Jira ticket description field ready only apart from Reporter ?

[Nitish Menon]

I have a requirement to restrict the assignee or other members from the team to restrict editing Description from editing once assigned. 
Only Reporter should have permission to edit it anytime in future. 

I am new to Jira. Pls. guide me with screenshots if possible or steps. 

[Joe Pitt]

JIRA doesn't have field level restrictions out of the box. You may be able to do it with a scripting plugin, but I see you're on the Free version so I don't know if you can install plugins. I don't use scripting so I can't help you there.