Project planning is based on the amount of work items to be done. In software development, the amount of work items is a suite of primary (custom) requirements.
Primary requirements can be issued by support department, customer representatives, marketing department, and project members. Usually, the amount of requirements is not known in advance. Moreover, they are constantly changing. Therefore, developers work with a primary requirement flow, which is usually displayed in the form of a log (backlog).
The backlog contains all incomplete primary requirements and is a source of primary requirements for project members.
To unify documenting primary requirements you can use issue and story templates. To create a template, open the issue or story card, and select "Create template based on” in Actions menu. After that, you can use the newly created template via orange button to create a primary requirement with predefined attributes (priority, state, assignee, iteration, etc.).
You can also create and edit templates in the project settings menu: Settings - Templates and Processes - Story/Issue Templates.
Use text templates to insert them quickly into the description of primary requirement after # symbol