Add GuardRails for Tool input and output

[LizeRaes]

The GuardRails are really awesome! It would be nice if we could also have them available to perform a check before executing a tool for these reasons:

• it is executing our code, so a vulnerability, I would be happy to run checks before performing eg. database operations
• tools break when the parameter syntax isn't respected, and depending on the model quality, it's a typical breaking point. We have withRetries() to mitigate this, but (esp. for dumber local models) it would be awesome if we could send back an error to the model like "argument missing, try again" or "variable 2 should be part of the following Enum: ..., make sure this condition is met and try calling the function again" to the model, and that this testing logic is wrapped in dedicated GuardRails

It would also be nice to have a GuardRail option for the Tool output, eg. to have a final check that no private user info is divulged, etc.

[geoand]

Thanks for reporting!

cc @cescoffier