[Feature]: Make Responses API the default for OpenAI

[vkryukov]

Feature Type

Provider feature extension

Provider (if applicable)

openai

Description

Note: This issue has a sister issue agentjido/llm_db#100 in LLMDB, where the metadata for some models needs to be updated.

Rationale: Responses API is the new, much improved version of Chat Completions API. All the new models support it, and some new models do not support Chat Completions anymore. In addition, all the advanced use cases (such as web search, code execution, etc.) require Responses API and do not work with Chat Completions.

There are only a handful of models that do not support Responses: 3.5-series, GPT-4 series (but note that 4o, 4.1 all support Responses), embeddings, and other special models.

Example Usage

No response

Can you contribute this?

Yes, I can submit a PR

[vkryukov]

We merged agentjido/llm_db#100 in the latest LLMDB, so even without the change for the defaults, all new models should be correctly routed to Responses API. However, it would still make sense to make it a default route eventually, now that it won't affect the correctness of the legacy models usage, which are now explicitly routed to Chat Completions API.