Hello For those who already used the vercel ai sdk on nextjs, is it to normal to have the func call called by the assistant instead of the tool or it's a bug ?

assistant: {"tool_calls":[ {"id": "call_cdAb7xKqrU7fkULE29xQ6HnY", "type": "function", "function": {"name": "write_ad", "arguments": "{"title":"Mocassins rouges en daim","description":"Vends une paire de mocassins en daim de couleur rouge, en très bon état. Taille non spécifiée, idéale pour un look estival chic.","category":{"leboncoin":"Chaussures"}}"}}]}