User Story Description should not be changed !!

[Sridhar Gandla]

I am planning to do Jira Automation... When User story is in active Sprint then User Story description field changes are not allowed (It's considered scope change).  To avoid scope changes, I am looking for Solution..  thinking of Automation using smart value compare using dates. 

#1) Compare user story Description change date with Sprint Start date ;  Can any one suggest smart value of  user story Description change date.. ?   Does really Jira store the date of only Description changed date...? I mean, particular field when it changed.. So, that I can use it for compassion.  Some one changes Description then it should revert to original details. or should not save...

#2) Any other better Solution that is applicable here? 

Using Post functions, change of work flow, Field restrictions  using validations  and add-on Solutions are not feasible Solutions et all. Jira Admin Team rejects those changes.  

[Sridhar Gandla]

Any solutions /Guidance from experts.   Simple way to understand the above is:  Is there any way to get  "Description" (ONLY) filed last changed date ?   Not the whole Issue...(like comments, Status, Summary, re-assignments) 

[Sridhar Gandla]

Any guidance on this please ?