How to handle tool use failures?

[rwtnb]

I have a simple tool which I'm using to describe images.

I'd like to fail the task if this tool fails for any reason.

For example, when an invalid url is passed as argument I don't want the agent generate an answer if it was unable to retrieve the image.
Graceful degradation is nice for some use cases, but for this one it will cause the agent to hallucinate.
How to prevent this behavior?