x-tags
`x-tags` appears on schema objects and properties. Its value is a list. Used by 44 providers across 213 OpenAPI documents. Observed values include `Model`. Consistent with documentation & dx — 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 | |
|---|---|---|
| schema | 1809 | |
| requestBody | 67 | |
| response | 603 | |
| parameter | 48 | |
| info | 50 | |
| operation | 2 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| array | 2557 |
| string | 22 |
Observed values
Sampled from the specifications, most frequent first.
Providers publishing it
All 44.
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 documentation & dx job.