An OpenAPI specification is a machine-readable description of a REST API. Developers use it to generate client code and to verify what an API does before they integrate.
The specification lists every endpoint, its parameters, and its responses in a standard format that tools can read.
An architect can evaluate an API in an afternoon, and a developer can generate a client library in minutes, instead of reading prose documentation and guessing.
The ResolveGrid REST API is published as an OpenAPI 3.1 specification, and the MCP server's tools are generated from it so the two never drift.