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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 3 Aug 2026

MCP elicitation schemas are validated with a clear error

You'll notice

Useful3 Signal0

MCP

A bad MCP elicitation schema now shows a clear error instead of a misleading reconnect message.

What

A malformed requestedSchema in an MCP elicitation now produces an InvalidParams error naming the constraint, rather than a misleading reconnect message.

Details

parse failure on requestedSchema is converted into an MCP InvalidParams error explaining the constraint
the completion notification handler is registered against the literal method name notifications/elicitation/complete

Evidence

notifications/elicitation/complete

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 →