unable to export description more than 500 char via document generator

[Chandu]

need document generator code to export description of more than 500 characters, along with image 

[Aron Gombas _Midori_]

You can generate PDF document from Jira issues with the Better PDF Exporter app.

It definitely supports 500+ characters and images both as attachments and also in the Description field:

(Discl. it is a paid and supported app developed by our team.)