Are you wanting the path to the ebook files to be included in the .json file? Have you tried the formats option?
Code:
calibredb list --for-machine --fields authors,title,formats with-library "D:\Calibre_Library\Intake" > "C:\users\user\desktop\foo.json"
Code:
{
"authors": "Harry Parker",
"formats": [
"D:/Calibre_Library/Intake/Harry Parker/The List Conspiracy (3750)/The List Conspiracy - Harry Parker.epub"
],
"id": 3750,
"title": "The List Conspiracy"
},