feat: Use finish_reason to check if response messages are tool_calls

[npuichigo]

• I have looked for existing issues (including closed) about this

Feature Request

feat: Use finish_reason to check if response messages are tool_calls

Motivation

rig/rig-core/src/providers/openai.rs

Line 381 in 8e6f197

tool_calls: Some(calls),

Currently we check if tool_calls is None, and actually some openai compatible servers like vllm just return empty list of tool_calls and the openai document does not express tool_calls as optional, so it's not save to just check it with None.

Proposal

Check the finish_reason field on tool_calls or add additional check for empty list

Alternatives

Maybe other ways exist to handle this

[0xMochan]

This is a good catch. A lot of our implementation for the openai spec actually has changed overtime due to a natural upgrade in LLM specs (all backwards compatible).