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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

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Claude Code v2.1.221

MCP request handlers moved to string method names and the new request object

Under the hood
Useful1 Signal0
MCP

MCP request handling was updated to a newer library shape, including prompts and task status updates.

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.

See this entry in the whole of v2.1.221 →