The `eslint-plugin-chai-expect-keywords` is an ESLint plugin designed to detect unsupported keywords in Chai.js `expect()` assertions, preventing silent test failures caused by invalid assertion chains. It is ideal for developers using Chai for testing who want to ensure their assertions are valid and maintainable. The plugin supports customization through options for additional allowed keywords and compatibility with Chai plugins like sinon-chai and chai-as-promised.