The description of an API contract should provide one to three paragraphs at the most about why an API contract exists, the nature of the relationship between producer and consumer, and what the business intent is being making APIs available.
Like the name of the API contract, the description should avoid focusing on what each API will do, as the APIs.json API description will cover the business details of each API, and the OpenAPI info description will cover the technical details of an API. The description of an API contract details the API contract itself which may take on different shapes and sizes, depending on wha the intent is.
An API contract description should speak to leadership and business stakeholders and take into consideration both the needs of the API producer and consumer, as well as any other relevant stakeholders. This description should be a summary that reflects the needs of everyone involved, and the properties each API contract possess, while perpetually aligning the business and technical sides of the contract.