### **Description:**

#### **Problem** When using customized deployment names for OpenAI/Azure GPT-5 models (such as `azure/something-something-gpt-5.5` or `my-prefix-gpt-5.4`), LiteLLM fails to route requests through the **Responses API Bridge**. This results in a validation error from OpenAI/Azure completions endpoints when utilizing tools with `reasoning_effort` enabled (e.g., `high`, `medium`, `low`): > `Function tools with reasoning_effort are not supported for something-something-gpt-5.5 in /v1/chat/completion`

#### **Root Cause** In [litellm/llms/openai/chat/gpt_5_transformation.py](cci:7://file:///c:/Users/fbellidopazo/Envs/sox/Lib/site-packages/litellm/llms/openai/chat/gpt_5_transformation.py:0:0-0:0), the [is_model_gpt_5_4_plus_model](cci:1://file:///c:/Users/fbellidopazo/Envs/sox/Lib/site-packages/litellm/llms/openai/chat/gpt_5_transformation.py:103:4-114:24) helper is used to identify whether a model is GPT-5.4 or newer to decide if bridging is necessary. However, it strictly enforces that the model name starts with `"gpt-5."`:

```python @classmethod def is_model_gpt_5_4_plus_model(cls, model: str) -> bool: """Check if the model is gpt-5.4 or newer (5.…