How do you add a title, description, and version to FastAPI auto-docs?

WHAT THIS TESTS: This question checks whether you know that FastAPI exposes first-class metadata configuration through the application constructor rather than forcing you to manipulate the OpenAPI schema manually. Interviewers want to see that you understand the framework's convention-over-configuration philosophy for API documentation and that you can configure docs without unnecessary boilerplate.

A GOOD ANSWER COVERS: First, the candidate should state that title, description, and version are keyword arguments passed directly to the FastAPI class when creating the app instance. Second, they should mention that these values automatically appear in the generated OpenAPI schema and therefore render in both Swagger UI and ReDoc without additional code. Third, a strong answer notes that the description field supports Markdown formatting for rich text. Fourth, the candidate might mention related metadata fields like terms_of_service, contact, or license_info to show deeper familiarity with the API surface and the OpenAPI specification.

COMMON WRONG ANSWERS: A red flag is suggesting that you must manually edit the OpenAPI schema dictionary or override the openapi method to inject metadata. Another mistake is proposing external documentation tools or static HTML as the primary solution. Some candidates incorrectly confuse the API version parameter with the OpenAPI specification version, which are separate concerns. A weaker answer might also omit any mention of where the metadata actually appears, suggesting the candidate has not looked at the generated docs.

LIKELY FOLLOW-UPS: The interviewer might ask how to customize the docs URL path, how to add metadata for specific tags, or how to disable the auto-generated documentation entirely in production. They may also probe whether you know how to add a license identifier or contact information using the same metadata pattern. A senior candidate might be asked how to serve custom static assets for the docs UI or how to conditionally expose the schema based on environment.

ONE CONCRETE EXAMPLE: A solid code sketch would show importing FastAPI and writing app = FastAPI with title set to Inventory Service, description set to Manages warehouse stock levels and supports Markdown, and version set to 2.5.0. After starting the server, navigating to the docs endpoint displays the title and version in the Swagger UI header and renders the description text accordingly. The candidate should emphasize that no additional decorators or route configuration are required because the framework handles OpenAPI generation natively.

Source: fastapi.tiangolo.com