{{ $isPage := or (and (ne .Type "posts") (in "section page" .Kind )) (and (eq .Type "posts") (eq .Kind "page")) }}
{{ $description := "" }}

{{ if .Description }}
  {{ $description = .Description }}
{{ else }}
  {{ if $isPage }}
    {{ $description = .Summary }}
  {{ else if .Site.Params.description }}
    {{ $description = .Site.Params.description }}
  {{ end }}
{{ end }}

{{ return $description }}