Checklist for everything that needs to be described and linked whenever a developer creates a new feature card on Trello so other people (or the same dev in the future) can understand the whole feature quicker.
Access Github Repo.
Checks are saved in your local storage
Include direct URL of product if possible.
Write a small summary describing the feature.
Chart the happy-path and describe it. Flowchart if too complex.
List documents related to feature. Specify document page and additional references if necessary. If the document is in a Trello card, link the card on this new one to avoid duplication.
Create a checklist and add as many items as possible as you think about the requirements of the feature (be broad here, make sure not to forget things that might seem obvious).
List permissions or user roles necessary to accomplish card. Describe them.
Think about default values for data. Describe them.
Think about error cases, include as checklists and define what to do if they happen. Examples of error cases: missing input, wrong input, missing data, duplicate data, missing permissions, going directly to a later step of a flow, offline user.
Think about edge cases related to side effects, include as checklists and define what to do when they happen. Are edge cases related? (For example, considering the feature "As a free user, I can become a premium user by paying a subscription plan with a credit card", an edge case is when the user pays but afterwards asks for a refund directly to his credit card operator. An appropriate response to this situation is having some sort of webhook on the application to get notified when an user cancels a payment.)
Think what messages and other feedback the user will see. Describe them. Include the copy (texts).
Include ideas and tips on implementation details. Example of tips: libraries and tools to use, debugging tips, performance bottlenecks, modularization tips, database modeling, code organization, data formats to use, etc.