MCP protected resource metadata

A remote MCP client discovers the authorization server for the particular protected MCP resource through resource metadata.

01 / The operating case

What changes in a real workflow?

An agent switches from the test MCP endpoint to the production endpoint, whose authorization server and supported scopes differ.

Trace the authority boundary
  1. 01Client / task
  2. 02MCP server
  3. 03Tool call + arguments
  4. 04Downstream effect

02 / Decision contract

What the executor must check

Resolve and validate the production resource metadata, use its authorization-server discovery, and bind token acquisition to the canonical resource URI.

InputPrincipal · task · action · target
DecisionGrant ancestry · policy · current state
ResultEnforce · record · verify outcome

03 / Failure and evidence

What goes wrong, and what can be proven?

Failure mode

Hard-coded authorization endpoints or copied test scopes lead to token confusion when the resource changes.

Evidence to retain

Keep metadata URL and version, discovered issuer, canonical resource and validation result; never log access tokens.

04 / Canonical scope

Why this reference stands alone

Resource indicators own token targeting; this page owns discovery of who can issue for the resource.

Protocol or attack trace

Discovery boundary

Sequence

Client moves from test resource R1 to production R2. R2 metadata identifies a different authorization server and canonical resource URI.

Negative test

Replace R2 metadata with an issuer not approved for R2; token acquisition must stop rather than fall back to R1.

Primary references

Read the underlying material

Architecture discussion

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