Error: Server does not support completions (required for completion/complete)
{
  "protocolVersion": "2024-11-05",
  "capabilities": {
    "tools": {}
  }
}
--- Quiet flag note ---
With --quiet: 'Error: Server does not support completions' printed to stdout (not suppressed)
Without --quiet: JSON output on stdout + error on stderr (exit 0 in both cases)
