How to search records in integration task in creator?

How to search records in integration task in creator?

How to search using integration task in creator 


searchString = {"zcrm_account_id:4050082000001001499"};

contactData = zoho.books.getRecords("Contacts","xxxxxx",searchString);

I get an error that third argument needs to be string, I tried to convert it to a string but it doesn't work then 

How to search it then? What's the correct way?