[openai] Fix missing tool usage check (system message)

[levunet]

Purpose

Fixed a bug where the commentary value was missing in Invalid Channel due to the absence of with_custom_tools value when fetching the system message.

[gemini-code-assist]

Code Review

This pull request addresses a bug that prevented tool usage with gpt-oss models. The issue was caused by the commentary channel being incorrectly removed from the system message, which is necessary for tool call functionality. The fix involves passing a with_custom_tools flag to the get_system_message function, determined by whether tools are present in the request. This change correctly preserves the commentary channel when tools are used. The fix is straightforward and effectively resolves the bug.

[alecsolder]

Looks good to me, it would be great to add a unit test for this, there are some examples here the test likely doesn't even need the model to run, just that the messages are being generated properly here.

[bbrowning]

A small nit would be that this will activate the commentary channel even if an empty list of tools is passed in, which is not uncommon. We could avoid that by using some like bool(request.tools) instead of request.tools is not None. But, I separately discovered this issue, Alec pointed me to this PR, and agree that this fix is needed to get accurate tool calling in Chat Completions with gpt-oss models.

Without this PR, I regularly see the models outputting non-built-in tool calls to the analysis channel, which isn't where they should go.

[chaunceyjiang]

LGTM

[bbrowning]

This PR substantially improves Chat Completions streaming tool call handling for Harmony models, especially for gpt-oss-20b. Without this PR, the 20b model often (and 120b sometimes) outputs tool calls to the analysis channel, which is wrong. We could adjust our streaming parser code to handle that, which is a fairly trivial change. However, the more appropriate fix is this PR, which activates the commentary channel when the request contains tools.

It may not reduce 100% of cases where tool calls inappropriately go to the analysis channel, but it makes a massive improvement.

[levunet]

@bbrowning
There are additional PRs that have modified the content you mentioned. I believe the harmony library improvements have resolved the issue close to 100%. If you need it, I recommend using that harmony code.

#24954
openai/harmony#76

[aarnphm]

Hopefully this fixes. Thanks for this!

[bbrowning]

Just a note that the CI failures look unrelated, as both are failing in a disk space check on the docker build jobs. This PR doesn't change anything that would impact free disk space on the builder nodes.