According to Google, the use of the API “allows Google to schedule job postings for a fresh crawl, which can lead to higher quality user traffic and job applicant satisfaction.”
To take advantage of the Indexing API, publishers must use job posting structured data on their pages. This structured data makes it easier for Google to identify key information about the job posting, such as company, location, date posted and salary.
The Indexing API is currently available only for job postings, which is understandable given that they are often time sensitive. By giving publishers the ability to notify Google of new postings and updates to existing postings, Google will be better able to maintain its job search.
The search giant has not announced any plans to make the Indexing API available for other types of content.