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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 v2.1.163

MCP Server Failure Notification

What

When MCP servers fail to connect or need authentication at startup, a structured tree notification now appears listing each affected server with its status and error details.

Details
  • The notification identifies whether each server needs authentication, has a config issue, or has failed for another reason.
  • Shows a summary count: N MCP server(s) not connected — run /mcp to authenticate, retry, or see details:
  • Servers requiring authentication are highlighted as errors; others as warnings.
  • Excludes IDE-attached servers (sse-ide, ws-ide types) and servers that are marked as claudeai-proxy.
Evidence

Notification text (search for "MCP server(s) not connected — run /mcp to authenticate, retry, or see details:")

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

See this entry in the whole of v2.1.163 →