policies with external tools

[boazdavid]

Hi,
Im developing a Python library to check that an LLM agent is calling tools according to a policy.
For example, in an airline agent: "All reservations can be cancelled within 24 hours of booking, or if the airline cancelled the flight."
As LLM can make wrong tool calls, the library will check the policy just before calling the tools. In this example, before the cancel_reservation(res_id) tool is invoked. The policy engine needs to get external data using the get_reservation(res_id) to check the reservation time stamp, and maybe get_flight_status(flight_id, date) to check if the flight was cancelled. I dont want to fetch all this data in advance and pass it in the input - as the data dependencies are complex and the parameters logic is embedded in the policy rules. Instead I want to populate the data incrementally - when needed.
I consider using OPA for this task. My concern is about accessing external data. in my case, the tools are invoked from Python, that will either run them as regular async Python functions (eg, do an sql query), or as REST calls.
I saw the option of http.send - but could not find much documentation.
Can you please recommend on the right approach to handle these requirements using OPA?
Thanks.

[anderseknert]

Hit there!

I dont want to fetch all this data in advance and pass it in the input - as the data dependencies are complex and the parameters logic is embedded in the policy rules. Instead I want to populate the data incrementally - when needed.

Sounds like you want a bundle server somewhere to manage data separately from the decision point. That's a good call. The docs on bundles are here: https://www.openpolicyagent.org/docs/management-bundles

But despite all the bells and whistles, a bundle is essentially just a tarball with your JSON data in it that you host somewhere for OPA to pull. When you update the bundle, OPA pulls down the update.

[boazdavid]

can the bundle API get dynamic parameters?
for example to have a bundle resources: reservations/{res_id} and flights/{flight_id}/{date}