from bs4 import BeautifulSoup
import requests
url = "http://sapo.pt"
url_get = requests.get(url)
soup = BeautifulSoup(url_get.content, 'lxml')
descricao = soup.find('meta', attrs={'name':'og:description'}) or soup.find('meta', attrs={'property':'description'}) or soup.find('meta', attrs={'name':'description'})    
print (descricao)