[clevengermatt]

The spec isn't hiding JSON Schema. There's a section on it with the dialect URI and the subset of keywords OBI uses: https://openbindings.com/spec#json-schema-dialect

That said, if it feels buried, I'll look at surfacing it more clearly.

You're right about the gRPC fidelity issues though. int64 precision, oneof vs oneOf semantics, enum value mapping, and well-known types all need careful handling when binding to Proto. The tradeoff is that JSON Schema is already the schema format inside OpenAPI, AsyncAPI, and MCP, so OBI can reference their schemas directly without translation. Proto would have given better fidelity for gRPC but required schema translation for every other binding. Picking JSON Schema prioritizes cross-binding reach over depth in any one protocol.

The fidelity limitations deserve clearer documentation. Adding that to the list. Thanks for pushing on this.