Proving a Client's Identity to an Authorization Server
An MCP client and the authorization server guarding a new server have usually never met, so before anything is authorized, the authorization server first has to decide whether it believes the client is who it claims to be. Explain why MCP's interoperability promise means a client and an authorization server often have no pre-existing relationship, and how that shapes registration. Apply the specification's four-path registration priority: pre-registered credentials, Client ID Metadata Documents, Dynamic Client Registration, and asking the user. Validate a Client ID Metadata Document the way an authorization server must: an exact clientid match, an https URL with a path, and the required metadata fields. Bind persisted client credentials to the authorization server that issued them, and explain why an authorization server change forces re-registration. Recognize the confused deputy risk a static-client-id proxy creates, and choose between the OAuth Client Credentials and Enterprise-Managed Authorization extensions for unattended or enterprise access. The whole case for MCP rests on one idea: a client written today should be able to use a server it has never seen before, and a server written today should be usable by a client its author never heard of. That is exactly the scenario ordinary OAuth was not built for. OAuth 2.1 assumes a client registers with an authorization server ahead of time, gets back a client…
Proving a Client's Identity to an Authorization Server: An MCP client and the authorization server guarding a new server have usually never met, so before…
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