Local models via llamacpp's responses API are no longer working

What version of Codex CLI is running?

v0.94.0

What subscription do you have?

Using a local model

Which model were you using?

gpt-oss-120b

What platform is your computer?

Archlinux

What terminal emulator and version are you using (if applicable)?

Gnome's default console

What issue are you seeing?

When using a model hosted by llamacpp with the following configuration:

[model_providers.llamacpp]
name = "llamacpp"
base_url = "http://127.0.0.1:3001/v1"
api_key = "sk-local"
wire_api = "responses"

[profiles.gpt-oss-120b]
model_provider = "llamacpp"
model = "gpt-oss-120b"
context_length = 131072

I am now seeing the following error messages:

{"error":{"code":400,"message":"'type' of tool must be 'function'","type":"invalid_request_error"}}

This used to work fine before. I updated both Codex & llamacpp, so I am not quite sure where the regression is.

What steps can reproduce the bug?

1. Configure a llamacpp backend with gpt-oss-120b
2. Point codex at that endpoint with the proper configuration
3. Run a query that requires a tool call.

What is the expected behavior?

Tool calls succeed

Additional information

_No response_