What problem does it solve? Writing API reference documentation by hand often produces docs that drift from the actual API contract, skip error cases, or leave developers unable to make a first successful call. This Skill guides the authoring of a published, consumer-facing API reference where every endpoint, field, and error traces back to the upstream api-spec contract, so a client developer can authenticate and integrate every operation from the reference alone. ## Core Features & Use Cases - Contract-derived coverage: Derives every endpoint, parameter, field type, error code, event, and auth scheme from the handed-in api-spec (OpenAPI, AsyncAPI, GraphQL SDL, or proto), never fabricating missing details. - Per-section authoring method: Covers getting-started, authentication flows, per-endpoint worked request/response examples, errors (RFC 9457 Problem Details), rate limits, pagination, webhooks, versioning, and deprecation. - Generation-adaptive mode: Adapts when the endpoint catalog is auto-generated from OpenAPI, shifting effort to onboarding narrative, example quality, and drift checking. - Amendment re-sync: Re-syncs an existing reference when the contract changes, handling deprecation-to-sunset lifecycles, stale sample re-checks, and doc versioning. - Use Case: Given an OpenAPI spec for a payments API, produce a complete developer reference with a copy-paste quickstart, OAuth flow walkthrough, worked examples per endpoint, and an error-code table. ## Quick Start Use authoring-api-reference to turn this OpenAPI spec into a consumer-facing API reference with a getting-started quickstart and worked examples for every endpoint.