Data & schema semantics · Size & shape

x-size-message

`x-size-message` appears on schema objects and properties. Its value is a string. Used by 2 providers across 7 OpenAPI documents. Observed values include `cannot be empty`, `Title is required`. Consistent with size & shape — this is inferred from where the key appears and what it carries, not from any published definition.

Data & schema semantics derived description
How this description was produced. It is assembled from what was measured in the corpus — where this key appears in a document, what shape its value takes, the values observed, and how many providers use it. It is not taken from a published definition, because for most extensions none exists. Read it as evidence, not as a specification. If you own this extension and want it described properly, tell us.
51 occurrences
7 documents
2 providers
purpose-named

Where it appears

Location in the documentOccurrences
schema 50
parameter 1

What its value looks like

Value shapeOccurrences
string51

Observed values

Sampled from the specifications, most frequent first.

cannot be emptyTitle is required

Providers publishing it

All 2.

agorapulsecosmo-tech

Why this is not in OpenAPI

Extensions exist because a provider needed something the specification would not carry. Most of what they hold is not the API contract at all — it is operational metadata about the contract: documentation, lifecycle, policy, provenance, and now agents. That metadata is usually better placed alongside the contract, in an Overlay or an APIs.json index, than crammed inside it. See everything else doing the data & schema semantics job.