x-source-title
`x-source-title` appears in the info block. Its value is a string. Used by 3 providers across 16 OpenAPI documents. Observed values include `B2B-API specifications`, `TFM POS API v1`, `Adv Custom API`, `Bid Check`. 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 | |
|---|---|---|
| info | 16 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| string | 16 |
Observed values
Sampled from the specifications, most frequent first.
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 documentation & dx job.