I want to include functionality in a model or python script so that a user could select a single polygon from a layer and use that as input for a a tool. So basically, I want a model version of the Select Features tool on the tools toolbar and I want to use the selected feature (i.e county) as input for a python script (tool). I have seen this interactive feature input, but do not think it will work exactly as I want.
The interactive feature input only works for a limited number of tools. You will have to document your script/model to indicate that a selection is required or all features will be used. You could limit it to the first feature by slicing off the first record a input.
You could follow @CurtisPrice1 suggestion to use GetCount and compare it to the total number of records and bail if getCount is > 1
Solved: Interactively Selecting Features as a Model Parame... - GeoNet, The Esri Community
They will soon catch on if they missed you parameter's help message
I am still not sure how to select a feature using interactive feature input. All I am seeing is creating a new feature. Is there a way to select a polygon from a layer and add that polygon to a new layer or export to new layer in model builder?