There are times when you need a description field added as a Metadata for content, but it keeps displaying the field as a tag list instead of a text field as shown below:
This is how you want it to appear:
This is how it is added instead:
The issue is that the system specifically checks for the spelling and capitalization of the field name. as shown here on the configuration screen when adding new Metadata:
You need to specifically use "description" as the field name. Using anything else such as "Description", "Desc", or "DESCRIPTION" will not be treated the same as the special description field name. Setting that properly and making sure to use "Meta Tag" as the Type, it will display the description metadata field as a text field.