OpenAPI Components Schema to Reference Docs Prompt

Use this prompt when you maintain an OpenAPI specification as the source of truth and need to generate human-readable reference documentation for each reusable schema defined under components/schemas. The job-to-be-done is producing accurate, standalone type definition pages that explain data models independently of any single endpoint. This is for API designers and documentation engineers who need to document inheritance chains (allOf), polymorphic structures (oneOf/anyOf), discriminator fields, nested object shapes, and cross-references to other schemas. The output should help developers understand the shape, constraints, and relationships of data models that appear across multiple endpoints without forcing them to reverse-engineer the raw JSON Schema.

Do not use this prompt for endpoint-specific request/response examples tied to paths, for generating OpenAPI specs from code, or for documenting operations like pagination parameters or authentication flows. The prompt assumes the spec is already valid and complete. It works best when your components/schemas section is well-factored, with schemas that use description fields, examples, and explicit discriminator mappings where polymorphism exists. If your spec is auto-generated from code annotations and lacks human-written descriptions, run a schema enrichment pass first. The prompt requires the full or partial OpenAPI spec as input, along with a target schema name and an output format specification (Markdown, MDX, or HTML).

Before wiring this into a documentation pipeline, verify that your spec passes OpenAPI validation and that all $ref pointers resolve correctly. The prompt will produce cross-reference links to other schemas, so your doc generation system must be able to resolve those links to actual pages. If your spec uses deeply nested inline schemas without $ref extraction, refactor them into named components first—this prompt is designed for the componentized pattern. For high-risk domains where schema accuracy is critical (payments, healthcare, auth), always include a human review step after generation to verify discriminator mappings, enum values, and nullable field documentation before publishing.

This prompt template is designed to process one OpenAPI component schema at a time, producing a complete, standalone reference page for a reusable type. It handles complex schema features including inheritance via allOf, polymorphism with oneOf/anyOf, discriminator mapping, nested object documentation, and cross-reference linking. The prompt expects you to extract a single schema object from your OpenAPI spec's components.schemas section and provide it as the [SCHEMA_OBJECT] placeholder. Loop over all schemas in your spec using the implementation harness described in the next section.

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You are an API documentation engineer. Your task is to generate a complete, standalone reference page for a reusable schema component extracted from an OpenAPI specification.

## INPUT SCHEMA
```json
[SCHEMA_OBJECT]

SCHEMA CONTEXT

• Schema name: [SCHEMA_NAME]
• OpenAPI version: [OPENAPI_VERSION]
• Base URL for cross-references: [BASE_REFERENCE_URL]
• Related schemas in this spec (for cross-reference linking): [RELATED_SCHEMA_NAMES]

OUTPUT REQUIREMENTS

Generate a reference page in Markdown with the following sections:

1. Schema Overview

• Schema name as an H2 heading
• One-sentence description of what this type represents
• Inheritance statement if allOf is present: "Extends [PARENT_SCHEMA] with additional properties"
• Polymorphism statement if oneOf or anyOf is present: "This is a polymorphic type. Valid variants include: [VARIANT_LIST]"
• Discriminator field and mapping table if discriminator is present

2. Properties Table

Generate a table with these columns: Property | Type | Required | Default | Constraints | Description

• Include all properties from the resolved schema (merge allOf chains)
• For nested objects, link to the nested schema reference page using [BASE_REFERENCE_URL]
• For arrays, specify item type and link if the item is a referenced schema
• Document nullable: true in the Constraints column
• Document enum values in the Constraints column as "Enum: [value1, value2, ...]"
• Document minimum, maximum, minLength, maxLength, pattern in Constraints
• Mark required fields with "Yes" based on the parent's required array

3. Polymorphic Variants (if oneOf or anyOf is present)

• For each variant, provide: variant name, discriminator value (if applicable), brief description, and link to the variant's reference page
• If anyOf is used, add a note: "Objects may match multiple variants simultaneously"

4. Example

• Provide a valid JSON example that satisfies the schema
• Include all required fields
• Show at least one optional field populated
• For polymorphic types, show one variant example and note that others are documented separately

5. Cross-References

• List schemas that reference this schema: [REFERENCED_BY]
• List schemas this schema references: [REFERENCES]

CONSTRAINTS

• Do not invent properties not present in the schema
• Use exact property names, types, and constraints from the schema
• If additionalProperties is false, note: "No additional properties allowed"
• If additionalProperties is a schema, document: "Additional properties must match [TYPE]"
• For oneOf schemas without a discriminator, warn: "No discriminator field specified. Variant selection requires content inspection"
• Do not generate documentation for inline schemas that are not named components
• Preserve $ref paths as cross-reference links, not inline expansions

OUTPUT FORMAT

Return only the Markdown reference page. No preamble, no commentary.

To adapt this prompt for your pipeline, replace the square-bracket placeholders with actual values before each invocation. [SCHEMA_OBJECT] should be the raw JSON of a single schema from components.schemas, not the entire spec. [RELATED_SCHEMA_NAMES] should be a comma-separated list of all schema names in the spec so the model can generate correct cross-reference links. [REFERENCED_BY] and [REFERENCES] can be populated by pre-processing your spec to build a dependency graph before calling the prompt—this avoids relying on the model to infer relationships it hasn't been given. If your spec uses circular references, add a [CIRCULAR_DEPENDENCIES] placeholder listing them explicitly so the model can note them in the Cross-References section rather than attempting to resolve them inline.

This prompt is designed to run as a batch processing step inside a documentation generation pipeline, not as a one-off chat interaction. The typical trigger is a change to an OpenAPI specification file in a repository. When the spec is updated, a CI/CD workflow extracts the components/schemas block, splits it into individual schema objects, and feeds each one to the prompt. The prompt produces a standalone Markdown reference page for each schema, which is then written to a documentation site's content directory. The harness must handle schema objects that contain oneOf, anyOf, allOf, discriminator, and $ref pointers, because these are the highest-risk areas for hallucinated or incomplete output.

Validation gates are mandatory before publication. After the model returns a Markdown page, run a structured validation step that checks: (1) every property name in the source schema appears in the output, (2) every $ref in the source schema is resolved to a correct cross-reference link in the output, (3) oneOf/anyOf variants are individually documented with their discriminator values, (4) required fields are marked as required, (5) enum values are fully enumerated, and (6) no invented properties or types appear. A JSON Schema validator can compare the source schema against a parsed representation of the output, flagging missing or extra fields. If validation fails, retry the prompt once with the validation errors appended as [CONSTRAINTS]. If the retry also fails, route to a human review queue with the source schema, the failed output, and the specific validation errors highlighted.

Model choice matters for schema fidelity. Use a model with strong structured output capabilities and a large context window. For OpenAPI specs with deeply nested $ref chains, the prompt must receive the full resolved schema context, not just the isolated component. Pre-process the spec to inline or summarize referenced schemas so the model has enough information to document inheritance and polymorphism correctly. Log every prompt invocation with the schema name, model version, token count, validation pass/fail status, and retry count. This audit trail is essential for debugging drift when the source spec changes and for demonstrating documentation quality to API governance stakeholders. Avoid wiring this prompt directly to a live documentation publish step without the validation gate—unvalidated schema docs erode developer trust faster than missing docs.