Source Intelligence
Follow Discord

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 v2.1.219 Home All releases ←olderv2.1.218 v2.1.220newer→
Claude Code v2.1.219

MCP error text is sanitized and credential-redacted before display

You'll notice
Useful3 Signal0
MCP

MCP error messages now hide credentials and strip weird characters before showing them to you.

What

Server-supplied error text reaching MCP UI surfaces is now normalized and scrubbed before it is interpolated into user-visible strings, and an invalid URL is no longer echoed back.

Details
  • Reconnect failures pass the tools-list error through a sanitizer (NFKC normalize, strip angle brackets and quote characters, collapse whitespace, truncate with an ellipsis) before interpolation into "Reconnected to ..., but fetching tools failed: ...".
  • The same sanitizer applies to a caught error message in the artifact/QR surface, and to messages embedded in Error reconnecting to and Failed to reconnect to .
  • Bearer, api-key and password-looking values are rewritten to [redacted].
  • MCP conflict notices in the transcript run their message and suggestion through a control-character stripper.
  • Schema-validation error formatting for MCP goes through the same path.
  • An invalid MCP url no longer echoes the URL back; the message is now a fixed string.
Evidence

'url' is not a valid URL. Update the server's config and reconnect., Error reconnecting to

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

See this entry in the whole of v2.1.219 →