What is OpenAPI?
OpenAPI (formerly Swagger) is a specification for describing HTTP APIs in a machine-readable format. An OpenAPI document (typically JSON or YAML) describes endpoints, request/response schemas, authentication, and examples in a standardised way that tools can use to generate clients, servers, documentation, and tests automatically.
OpenAPI 3.1 (the current version) aligns fully with JSON Schema, allowing reuse of existing schema definitions and enabling richer validation. An OpenAPI document consists of an `info` block (title, version, description), `paths` (endpoints with operations), `components` (reusable schemas, parameters, responses), and optional security schemes.
For AI agents, the OpenAPI spec is a critical discovery surface. Agents can load `/openapi.json`, parse the available operations, understand input and output shapes, and call any tool without prior knowledge of its API. Tools like Claude, ChatGPT plugins, and LangChain's OpenAPI agent all support this pattern.
quickhelp.dev maintains an aggregated OpenAPI 3.1 document at `/openapi.json`. Each tool's `inputSchema` and `outputSchema` (defined as Zod schemas in the manifest) are automatically compiled to JSON Schema and embedded in the OpenAPI document. Adding a new tool automatically extends the spec.
Use the spec to generate client SDKs in any language, import it into Postman or Insomnia, or point an AI agent at it for tool discovery.