{"version":"2.1.219","anchor":"mcp-connection-failures-can-carry-an-extra-display-detail","canonical_anchor":"mcp-connection-failures-can-carry-an-extra-display-detail","heading":"MCP connection failures can carry an extra display detail","tier":"notice","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.219\/e\/mcp-connection-failures-can-carry-an-extra-display-detail","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.219","markdown":"### MCP connection failures can carry an extra display detail\n\nFailed MCP connections now tell you why, with the error detail shown in list and get output.\n\n**What**\n\nFailed MCP connections can now attach a `displayDetail` explaining why, and the CLI surfaces it instead of just showing a bare status.\n\n**Details**\n\n- `displayDetail` is optional, threaded through the failure constructor and appended to the user-visible error.\n- The Authorization-header rejection path attaches `Error detail:` plus the server response body when that body is non-empty.\n- `claude mcp list` builds its status line as the status, an em dash and the issue; `claude mcp get` prints an `Issue:` line.\n- The \"! Connected \u00b7 tools fetch failed\" status now carries the underlying error as its issue.\n\n**Evidence**\n\n`displayDetail`\n\n- Area: MCP\n- Names: `claude mcp list`, `claude mcp get`\n- Tier: You'll notice\n- Useful: 4\/5\n- Signal: 0\/5"}