Ec2 cli tools are old and are not maintained by AWS anymore. Use aws-cli instead. Refer this link which details how to set-up and configure aws-cli.
using aws-cli, its a one time installation which support almost all the AWS Services. with older CLI tools, you had to configure CLI for each and every service separately.
also aws-cli provides output in JSON format, hence it is extremely easy to parse output. This feature was missing from all the older CLI tools and parsing the output was the most painful task.
Also older CLI tools were java dependent, whereas aws-cli works on python and in my experience, I have found its comparatively faster than the older cli tools.