Hello @Daniele_Poletti, welcome to the community forums!

Without having much context on the rest of your application, I see one thing in the code provided that might be confusing your app: the JSON parse function.

Have you tried simplifying your code to:

const db = client.db(‘expManger’);
const collection = db.collection(‘cdc’);

const doc = {"description": "prova testo fisso"};
const result = await collection.insertOne(doc);

console.log(`New document with _id: ${result.insertedId}`)