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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 v2.1.219

MCP connection failures can carry an extra display detail

You'll notice
Useful4 Signal0
MCP

Failed MCP connections now tell you why, with the error detail shown in list and get output.

claude mcp listclaude mcp get
What

Failed MCP connections can now attach a displayDetail explaining why, and the CLI surfaces it instead of just showing a bare status.

Details
  • displayDetail is optional, threaded through the failure constructor and appended to the user-visible error.
  • The Authorization-header rejection path attaches Error detail: plus the server response body when that body is non-empty.
  • claude mcp list builds its status line as the status, an em dash and the issue; claude mcp get prints an Issue: line.
  • The "! Connected ยท tools fetch failed" status now carries the underlying error as its issue.
Evidence

displayDetail

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.219 →