Hi Rémi Fayolle, thanks for your question. I confirm that history is only for the instructions.
It never happened before 🤔 Sometimes when you delete / move a folder that the tool is plug to, it removes the tool but it's rare. Are your sure that nobody on your side edited the agent?
Unfortunately, there isn't much we can do to retrieve it 😞 I'll flag this to the team in case it's recurring