With client_secret_basic the MCP SDK sets the Basic header and still sends
client_id in the body; Linear refuses that as two authentication methods.
Token and refresh requests now drop the body client_id when the Basic
header is set, as RFC 6749 describes.
mcp 2.x reads code, state and the RFC 9207 iss off the callback handler's
result; the handler still returned a (code, state) tuple, so every MCP
sign-in failed after the user approved it. The callback route now keeps the
issuer too, since servers that advertise it (Linear) refuse a sign-in
without it.
Linear and Sentry publish https://host/mcp as their protected resource.
DocsGPTOAuth gave the MCP SDK only the server's origin, so the SDK's
resource check (RFC 8707) failed before sign-in with "Protected resource
https://mcp.linear.app/mcp does not match expected
https://mcp.linear.app". The provider now gets the full MCP URL; servers
that publish their origin still pass, and tokens stay keyed by origin.
Covers creating and editing tools whose key lives on a connection, the
MCP action refresh, and the auth, ownership and error branches of the
connections API. Editing a tool's key now also recovers a connection
whose stored credentials can no longer be decrypted.
arc53-machine