protected-resource metadata
A JSON document, defined by RFC 9728, that an OAuth-protected server publishes to say which authorisation servers issue its tokens, which scopes exist and which resource a token is for. MCP servers that require a login are expected to publish it, so a client can discover how to log in.
What protected-resource metadata does not show
A server without it leaves the client guessing, and a client that does not check its resource field can be pointed at another host.
Where protected-resource metadata comes up on this site
- How to check an MCP server before an AI agent connects to itA server that needs sign-in should answer 401 with a WWW-Authenticate header pointing to its protected-resource metadata, so a client can find the right authorisation server instead of guessing.
- 25,983 MCP endpoints from the registry: what they answer, and the eleven whose tools talk to the model6,422 doors, and 712 with no sign on them A server that asks for credentials is supposed to say where to get them: a WWW-Authenticate header pointing at its protected-resource metadata, which names the authorization server, which names the scopes.
- MCP servers that ask for a login: what 1,366 request firstFor each server that asked, we read only what an unauthenticated client can read: the challenge it returns, its scopes , its protected-resource metadata and its authorisation server’s metadata.
Terms this definition uses
Related terms in Agents and protocols
How autonomous agents plan, remember, call tools and talk to each other, including MCP and A2A, and where each step can go wrong.
token audience · PKCE · refresh token · default scope request · tool poisoning · tool lockfile · MCP rug pull · tool shadowing · MCP preflight · agent manifest · stapled verdict · verdict over DNS · agentic web · preflight · decision receipt · receipt header · action assurance · resolve answer · freshness window · AI agent · Agent loop · Planner · Executor · Agent memory · Working memory · Long-term memory · Episodic memory · Semantic memory · Agent orchestration · Multi-agent system · Agent handoff · Delegation · Tool result · Tool schema · Tool description · Tool selection · Tool permission · Human-in-the-loop · Human-on-the-loop · Approval gate · Agent sandbox · Agent identity · Agent authorization · Agent discovery · Capability negotiation · MCP server · MCP client · MCP host · MCP resource · MCP prompt · MCP tool · MCP transport · JSON-RPC · A2A protocol · A2A client · A2A server · Agent skill · Agent task · Agent artifact · WebMCP · A2A
Questions about protected-resource metadata
What is protected-resource metadata?
A JSON document, defined by RFC 9728, that an OAuth-protected server publishes to say which authorisation servers issue its tokens, which scopes exist and which resource a token is for. MCP servers that require a login are expected to publish it, so a client can discover how to log in.
What does protected-resource metadata not show or guarantee?
A server without it leaves the client guessing, and a client that does not check its resource field can be pointed at another host.
Which area of the glossary does protected-resource metadata belong to?
Agents and protocols: How autonomous agents plan, remember, call tools and talk to each other, including MCP and A2A, and where each step can go wrong.
See it in the full glossary · 731 terms across 19 areas.