The Twilio Serverless Toolkit is a suite of command line tooling designed to help developers create and deploy functions and assets to Twilio Runtime. It provides a range of features, including pre-built functions, the ability to start or add to projects using templates, changing the deploy directory to accommodate different application structures, building serverless projects in TypeScript, fetching or tailing function logs, and testing projects with ngrok. These features aim to make it easier for developers to create and deploy Twilio applications, improving their workflow and productivity.