Which API allows querying and discovering metadata about Tableau content?

The Metadata API is specifically designed for querying and discovering metadata about Tableau content. It enables users to explore the relationships between different Tableau assets, such as workbooks, datasources, and fields. By utilizing this API, organizations can extract detailed information about their Tableau environment, assess its structure, and understand how data flows through various dashboards and reports.

This API provides functionalities that allow users to identify dependencies, track lineage, and gain insights into the usage of content within Tableau Server or Tableau Online. It's particularly valuable for data governance and analytics, enabling users to manage metadata effectively across their Tableau ecosystem.

In contrast, other APIs serve different purposes. The Document API is focused on manipulating Tableau workbook files directly. The REST API is broader in scope, allowing for a variety of operations like user management, but it doesn't specialize solely in metadata. The Extensions API enables developers to create interactive extensions for dashboards, which also operates outside the scope of metadata querying. Thus, the Metadata API stands out as the correct choice for tasks related to understanding and managing Tableau content at the metadata level.