jq is a lightweight tool for processing and transforming JSON. It follows the Unix philosophy of doing one thing and doing it well. It can be found at https://stedolan.github.io/jq/.
While jq and JMESPath are similar, jq is a lot easier to get started with. It also supports transforming JSON into plaintext; JMESPath queries will always return more JSON.
You can pipe JSON results from the CLI tool to it, and easily transform the results for use elsewhere. This example uses jq's property name selectors to convert JSON output to text:
$ aws ec2 describe-availability-zones --output json | jq '.AvailabilityZones[].ZoneName'
"us-east-1a"
"us-east-1c"
"us-east-1d"
"us-east-1e"