Design specs are things that you can use to help you make a design. They include information about the target audience and the product's background, such as the feature set and purpose. I would recommend this https://masterbundles.com to download best templates. This type of specification is typically written in English and contains a summary of what is expected from your design and how it will function. The designer can also use other methods such as brainstorming, sketching and wireframe testing to come up with a better idea of what he/she needs to do.

As of now, the Developer needs to visit every screen and download the assets inside that artboard. Sometimes, They just need the complete assets used in the entire design or artboards.

Maybe - They can select multiple artboards and export assets used in those artboards

Or - Select all the artboards at once and export complete assets as .zip file.

Sometimes developers want assets prepared in a special way, would there be a possibility to have an option to add a zip file of your own assets in the same developer link we are sharing with them?