How to use AI to document an API from its contract

Documenting an API with AI from its contract means translating a specification into useful instructions without inventing features. The document must distinguish declared behavior from details still needing confirmation.

We will work with a fictional task API. No real requests, credentials or assumptions about an internet service are involved in this documentation exercise.

Choose the source of truth

Identify which contract version you are documenting. If old examples, notes and a current specification coexist, explain each source’s role before requesting text.

The OpenAPI Specification defines a way to describe HTTP interfaces. Here it is a structural reference; writing documentation does not require migrating a project’s contract.

An OpenAPI description does not prove that an implementation already behaves accordingly. Record whether the material is an approved contract, a proposal or a snapshot extracted from a system.

1. Read one operation at a time

Start with path, method, parameters and responses. For fictional GET /tasks/{id}, the identifier belongs in the path and the result is a task or an indication that no task was found.

Contract element	Exercise example
Method and path	GET /tasks/{id}
Parameter	id, required text in the path
Response 200	Object containing id and title
Response 404	Task not found

This table is our simplified fictional contract description. Do not add pagination, task creation or filters merely because other APIs commonly offer them.

Review required versus optional fields separately. An example containing a field does not by itself establish that every response is required to include it.

2. List undeclared details

The contract should clarify authentication, required fields and error formats when those elements belong to the interface. If a source omits a detail, mark the absence.

“Authentication not described” differs from “authentication unnecessary”. Likewise, a documented 404 response does not automatically reveal its complete error body.

Separate documentation questions from implementation questions. The team may need to complete the contract itself before a consistent guide can be written.

3. Request a guide faithful to the operation

Supply necessary material only and require examples to follow declared fields. Request a gaps section containing questions the source cannot answer yet.

Document this fictional HTTP operation from its supplied contract.
Explain purpose, method, path, parameters and declared responses.
Use synthetic examples compatible with existing fields.
Do not invent authentication, limits, pagination or error messages.
Mark missing details as “not stated in the contract”.
Do not make network requests.

AI can help turn technical terms into clear instructions. Fidelity still depends on comparing its result with the original specification.

4. Review examples field by field

Check that identifiers appear in the right location and types remain unchanged. Documentation converting text into a number can lead somebody to construct an invalid request.

Label synthetic responses as examples and use known fields only. Do not present an AI-created object as output captured from a server.

Review implicit promises as well: response times, availability and filter support need a source. Silence in a contract does not authorize filling gaps with imagined conventions.

Do not include real tokens in sample headers. If authentication remains unspecified, preserve that question rather than fabricating a credential format to make the page look complete.

5. Test reading without an integration

Ask another reader to locate the method, required parameter and two described outcomes. They should also identify which information remains pending.

Your completion criterion is traceable documentation: every operational claim points to a contract element or is clearly marked as a question.

Keep the text tied to its version

Record version, date and reviewer. When an operation changes, review examples, types and responses before republishing the guide.

Common mistakes include inventing an authentication token, copying examples from another API and confusing a proposal with implemented functionality.

For organizing content review, use the AI process-documentation guide while keeping the technical contract authoritative for operations.

Frequently asked questions

Does a specification prove the API is implemented?

No. Identify whether it is an approved contract, proposal or system snapshot and confirm implementation separately.

Does missing authentication documentation mean unrestricted access?

No. It means that detail is unspecified and needs clarification.

How should I check an AI-created example?

Compare fields, types, parameters and responses with the contract and label the example synthetic.