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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.

← All of v2.1.242 Home All releases ←olderv2.1.241 v2.1.243newer→

Claude Code v2.1.242 24 Aug 2026

Malformed MCP capability declarations on published artifacts explain the fix

You'll notice

Useful2 Signal2

Artifacts

Bad MCP capability declarations on a published artifact now come with a diagnosis and a fix.

What

Publishing an artifact that declares MCP capabilities incorrectly now gets a specific diagnosis and remedy for each case instead of a generic rejection.

Details

Covers: the declaration not being an object, no servers listed, no tools listed, a connector id used where a server name belongs, a tool name in the server slot, and a name that cannot be declared until it is renamed in claude.ai.

Evidence

is a connector id, which no viewer can resolve

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.242 →