[FunnyLookinHat]

> Server authors working on large systems likely already have an OAuth 2.0 API.

I think this biases towards sufficiently large engineering organizations where OAuth 2.0 was identified as necessary for some part of their requirements. In most organizations, they're still using `x-<orgname>-token` headers and the like to do auth.

I'm not sure that there's a better / easier way to do Auth with this use case, but it does present a signficant hurdle to adoption for those who have an API (even one ready for JSON-RPC!) that is practically ready to be exposed via MCP.

[motorest]

> I think this biases towards sufficiently large engineering organizations where OAuth 2.0 was identified as necessary for some part of their requirements. In most organizations, they're still using `x-<orgname>-token` headers and the like to do auth.

I don't think that's it. Auth is a critical system in any organization, and larger organizations actually present more resistance to change, particularly in business critical areas. If anything, smaller orgs gave an easier time migrating critical systems such as authentication.