OAuth for MCP
The Model Context Protocol's authorization specification defines how an MCP client obtains and presents credentials to an MCP server using OAuth 2.1, rather than leaving every implementer to invent its own authentication scheme. An MCP server acting as an OAuth resource server can require a client to complete an authorization flow before it will serve a request, and the specification's security guidance specifically warns against naive "token passthrough" -- forwarding a token issued for one service straight through to another -- since a token isn't guaranteed to be valid for the second service's intended audience, a failure mode related to the confused deputy problem. Because MCP servers are increasingly exposed to agents acting with real tool access, following this specification rather than skipping authorization, or implementing it incorrectly, is what actually determines whether a server's tools are protected from unauthorized callers.
By AdminKit team, Netbase JSC · Updated