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VerifiedStandard or protocol

RFC 9728, OAuth 2.0 protected resource metadata

Published in April 2025, this defines a metadata document a protected resource publishes so a client can discover how to talk to it, including which authorization servers it trusts. It is the discovery leg of agent authorization: an agent meeting an unfamiliar server learns where to get a token instead of guessing.

The verdict

Verified

The document exists. The ledger fetched it at its publisher and quotes it.

Key facts

What the sources say

Record ID
AAL-2026-0009
Kind
Standard or protocol
Jurisdiction
Global
Last verified
Added
  • The specification defines a metadata format an OAuth client or authorization server can use to obtain the information needed to interact with a protected resource.
  • MCP servers must implement it, and MCP clients must use it for authorization server discovery.
  • The metadata is reached from a WWW-Authenticate header on a 401 response, so discovery starts from a refusal.
  • Section 7.7 of the document is the basis for blocking private and reserved address ranges when fetching discovery URLs.

Dimension by dimension

2 dimensions, each one stated, silent or open

Authorization, Identity. Stated means the document you can open below says it; silent means the ledger read the document and it does not.

AuthorizationStated
It tells a client which authorization servers a resource accepts tokens from, which is the first decision in any agent to tool handshake.RFC Editor, RFC 9728, primary source, 1 April 2025.
IdentityStated
The resource names itself in its own metadata, giving the client a canonical identifier to bind a token to.RFC Editor, RFC 9728, primary source, 1 April 2025.

What it changes

For a team deploying an agent

This is what lets an agent connect to a tool nobody pre configured. It is also a server side request forgery surface, because the agent is fetching URLs a remote server chose. Require HTTPS, block private ranges, and validate redirect targets before your client follows anything it discovered.

Sources

What this record was verified against

  1. RFC Editor, RFC 9728Primary · 1 April 2025

Related

Records that sit beside this one

Cite this record

Free to reuse under CC BY 4.0, with attribution. The record ID AAL-2026-0009 is permanent and is never reused.

In a sentence
According to the GAGE Agent Authority Ledger (as of 15 September 2026), rfc 9728, oauth 2.0 protected resource metadata.
APA
GAGE (Global Academy of Generative-AI Education). (2026). RFC 9728, OAuth 2.0 protected resource metadata. Agent Authority Ledger. Retrieved 15 September 2026, from https://www.gage.academy/tools/agent-authority-ledger/records/AAL-2026-0009-rfc-9728-oauth-2-0-protected-resource-metadata
MLA
"RFC 9728, OAuth 2.0 protected resource metadata." Agent Authority Ledger, GAGE (Global Academy of Generative-AI Education), 15 September 2026, https://www.gage.academy/tools/agent-authority-ledger/records/AAL-2026-0009-rfc-9728-oauth-2-0-protected-resource-metadata.
Chicago
GAGE (Global Academy of Generative-AI Education). "RFC 9728, OAuth 2.0 protected resource metadata." Agent Authority Ledger. Last modified 15 September 2026. https://www.gage.academy/tools/agent-authority-ledger/records/AAL-2026-0009-rfc-9728-oauth-2-0-protected-resource-metadata.
Permalink
https://www.gage.academy/tools/agent-authority-ledger/records/AAL-2026-0009-rfc-9728-oauth-2-0-protected-resource-metadata

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