In her talk at RubyConf 2021, Sarah Reid addresses the crucial issue of API documentation and introduces Rswag as a solution to automate and improve API documentation practices. She emphasizes that good documentation is vital for any successful software application, particularly for APIs, which can often feel like 'black boxes' for developers due to insufficient documentation, leading to inefficiencies and frustrations.

Key points discussed in the presentation include:

- Importance of Documentation: Reid relates her firsthand experiences of struggling with poor documentation, highlighting how effective documentation enhances efficiency and developer experience. Great code is rendered useless without corresponding documentation.

- Common Documentation Problems: She shares her team's experiences with outdated and inaccurate documentation, stating that human error significantly affects documentation quality. Only the engineers can keep it updated, which places a heavy burden on them.

- Introduction to Rswag: Rswag is a tool that integrates with Rails and uses the OpenAPI specification to generate API documentation from written specs. Reid explains how it binds the API and its documentation together, ensuring synchronization and reducing discrepancies.

- OpenAPI Specification: She explains the OpenAPI standard as a language-agnostic interface that provides a consistent way to describe the capabilities and responses of RESTful APIs, allowing developers to naturally understand the service without inspecting code or network traffic.

- Demonstration of Rswag: Reid showcases Rswag in action, demonstrating how easy it is to generate documentation through simple integration. She illustrates adding an attribute to an API response and how running Rswag updates the documentation automatically.

- Swagger UI: The presentation highlights the interactive interface generated from the API schema, allowing developers and users to test API endpoints directly from the documentation, facilitating smoother interactions and debugging.

- Conclusion: Reid urges engineers to consider automating their API documentation to save time and reduce the frustration associated with maintaining documentation, ultimately enhancing the user experience and increasing API adoption.

In conclusion, Sarah Reid's presentation provides a compelling case for using Rswag to alleviate the burdens of API documentation, reinforcing that documentation can and should be automated for better software development practices.