Control Room API for getting folder parentid/id

Has anyone successfully been able to drill down using the file/list control room api to only get a list of folder parentid/ids? We are currently working on automating folder creation/edit/delete/ect but have not been able to extract just folder ids/parent ids. When we run the api we mostly get a list of all files containing a specific name or file path within them and have not been able to filter down further to get just folder information. Below are a few examples used.. hopefully someone has successfully done this for just folder ids or can see something i am doing wrong..

Examples used: 

{ "filter":{ "operator":"substring", "operands": [], "field":"path", "value":"Automation Anywhere\\Bots\\My Tasks\\$varParentFolder$" } }

{ "filter":{ "operator":"substring",  "field":"path", "value":"$varParentFolder$" } }

This returned nothing but a count: 

{ "filter":{ "operator":"eq", "operands": [], "field":"name", "value":"$varParentFolder$" } }

any help or insight is greatly appreciated!