x-gitbook-description-html
`x-gitbook-description-html` appears on schema objects and properties. Its value is a structured object. Used by 3 providers across 6 OpenAPI documents. Consistent with data & schema semantics — this is inferred from where the key appears and what it carries, not from any published definition.
Where it appears
| Location in the document | Occurrences | |
|---|---|---|
| info | 6 | |
| requestBody | 4 | |
| schema | 442 | |
| response | 42 | |
| operation | 24 | |
| parameter | 32 | |
| securityScheme | 2 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| string | 271 |
| object | 281 |
Observed values
Sampled from the specifications, most frequent first.
General numeral field that accepts any numeric data you want to send. Appears
General field that accepts a date and time in ISO 8601 format you want to sen
Number of results to return per page.
The initial index from which to return the results.
Invalid data
The unique reference to the queued submission.
Indicates that the request failed.
The name of the field that caused the error.
Providers publishing it
All 3.
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.