Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
MCPArea: what it touches
Internal ChangesKind: in v2.1.221,
Internal ChangesSection of the release
What
Internal MCP call sites were updated to the newer SDK shape.
Details
Handlers register by literal method name and read the abort signal off the request wrapper rather than a separate extra argument.
Elicitation registers on "elicitation/create" and uses the request's own signal.
Task status notifications register on "notifications/tasks/status" with an explicit params schema and read taskId and status off the notification directly.
Evidence
notifications/tasks/status
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeChanged /status to show the session kind: interactive, or a background job that is attached or unattended
