The CircleCI command line interface (CLI) tool allows developers to build, validate, and test their pipeline jobs locally, streamlining the development process by reducing unnecessary code commits and resource consumption on the platform. To use the CLI tool effectively, developers need to understand key CircleCI concepts such as pipelines, workflows, executors, jobs, and steps, which are fundamental in composing a CI pipeline configuration. The platform, known for automating continuous integration and delivery tasks, provides feedback on code through a configuration file that dictates how and when actions are performed. While the CLI tool offers capabilities like debugging, validating configurations, and running jobs locally, it has limitations, such as not supporting local execution of entire pipelines or workflows. The tutorial demonstrates creating and testing jobs locally, using environment variables, implementing CircleCI orbs for automation, and handling security vulnerabilities with tools like Snyk, all while emphasizing the importance of maintaining secure and efficient development practices.