x-usage-request-limit-remaining
`x-usage-request-limit-remaining` appears on header objects. Its value is a structured object. Used by a single provider across 1 OpenAPI document. Consistent with data & schema semantics — this is inferred from where the key appears and what it carries, not from any published definition.
headers: map, which is the same syntactic position an extension
key occupies — but OpenAPI models headers natively and this is not extending
anything. It is listed here because it turns up when you inventory the
x- namespace, and leaving it out would hide why the namespace looks
bigger than it is.
Where it appears
| Location in the document | Occurrences | |
|---|---|---|
| header | 11 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| object | 11 |
Providers publishing it
All 1.
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.
Work with this as data
Every extension here is available over the APIs.io API and to AI agents over MCP. OpenAPI Extensions is not yet its own endpoint on the v1 API. Reach it through catalog search and the tag graph, or the MCP server.
MCP server
One button, every client — Claude, Cursor, VS Code and the rest.
https://apis.io/mcp
Tools for openapi extensions
3 MCP tools reach this
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.resolveTurn a domain, URL or GitHub org into the provider it belongs to.find_cohortsEvery scored population of providers in the catalog.
Call it yourself
curl for this page
curl "https://apis.io/api/v1/search?q=x-usage-request-limit-remaining&limit=10"curl "https://apis.io/api/v1/tags/x-usage-request-limit-remaining"Discovery needs no key. Ratings and market analysis are Pro.