> ## Documentation Index
> Fetch the complete documentation index at: https://docs.laozhang.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# GPT-6 now calls tools in Chat Completions: use it in Cline and Cherry Studio

> Since November 4, 2026, GPT-6, GPT-6.1, and GPT-5.6 reasoning models on LaoZhang API can reason and call tools in the same Chat Completions request. The 'Function tools with reasoning_effort are not supported' error is gone, max_tokens is accepted, prices are unchanged, and existing code keeps working.

Clients that use Chat Completions, such as Cline and Cherry Studio, used to get a 400 as soon as GPT-6 tried to call a tool, so you had to switch models or move to Responses. The same request now returns tool calls.

* **Published**: November 4, 2026
* **Last verified**: November 4, 2026
* **Status**: Active

## Key facts

| Item | Details |
| - | - |
| Endpoint | `POST /v1/chat/completions`; Responses (`POST /v1/responses`) works as before |
| Token | `default`, `vip`, or `svip` group, with Usage first or Usage-based billing |
| Reasoning effort | Send `reasoning_effort` together with `tools`; accepted values are unchanged |
| `max_tokens` | Accepted; no need to switch to `max_completion_tokens` |
| Price | Unchanged; billed per token at each model's rate, listed in the [model catalog](https://docs.laozhang.ai/en/models.md) |

Models covered:

* GPT-6: `gpt-6-astra`, `gpt-6-sol`, `gpt-6-luna`
* GPT-6.1: `gpt-6.1-sol`, `gpt-6.1-terra`
* GPT-5.6: `gpt-5.6-sol`, `gpt-5.6-luna`, `gpt-5.6-terra`

## What this unlocks

| Use case | Before | Now |
| - | - | - |
| Cline and other coding agents on OpenAI Compatible | GPT-6 failed; you had to pick another model | Pick `gpt-6.1-sol` |
| Cherry Studio with MCP tools on | Error; you had to switch models | Use `gpt-6-sol` |
| Other agents and desktop clients that speak Chat Completions | Every tool call returned 400 | Tool calls come back normally |
| Your own agent built on the OpenAI SDK | Rewrite it for Responses | Keep `chat.completions.create` |

## How to use it

Add `tools` to your existing Chat Completions request and set reasoning effort as usual. Install the SDK first (`python -m pip install openai`) and set the `LAOZHANG_API_KEY` environment variable:

```python theme={null}
import os

from openai import OpenAI

client = OpenAI(api_key=os.environ["LAOZHANG_API_KEY"], base_url="https://api.laozhang.ai/v1")

response = client.chat.completions.create(
    model="gpt-6.1-sol",
    reasoning_effort="high",
    messages=[{"role": "user", "content": "What's the weather in Paris right now?"}],
    tools=[{
        "type": "function",
        "function": {
            "name": "get_weather",
            "description": "Get the current weather for a city",
            "parameters": {
                "type": "object",
                "properties": {"city": {"type": "string"}},
                "required": ["city"],
            },
        },
    }],
)

for call in response.choices[0].message.tool_calls:
    print(call.function.name, call.function.arguments)
```

The script prints the function the model wants to call and its arguments, for example `get_weather {"city":"Paris"}`. Run the function, send the result back as a `tool` message, and the model writes the final answer. The full two-turn example is in [function calling](https://docs.laozhang.ai/en/api-capabilities/function-calling.md#chat-completions-example).

## What hasn't changed

* **Reasoning effort values**: `gpt-6-astra` and `gpt-6.1-sol` don't accept `none`.
* **`max` reasoning effort**: in Chat Completions, `gpt-6.1-sol` goes up to `xhigh`; use Responses for `max`.
* **Sampling parameters**: unless reasoning effort is `none`, leave out `temperature`, `top_p`, and similar parameters. See the [GPT-6 launch announcement](https://docs.laozhang.ai/en/announcements/gpt-6-launch-2026-09.md#check-your-request-parameters-before-you-switch).
* **Web search**: still available only through Responses; see [web search](https://docs.laozhang.ai/en/api-capabilities/web-search.md).

## Who is affected

* **You send tools to GPT-6 or GPT-5.6 through Chat Completions**: requests that used to fail now work. No changes needed.
* **You moved to Responses for tool calling**: it keeps working, and you don't need to move back.
* **You set reasoning effort to `none` so tools would work**: that still works. To let the model reason, set `low` or higher.
* **Not affected**: other models and all Responses requests.

## FAQ

### Is "Function tools with reasoning\_effort are not supported" gone?

Not since November 4, 2026. The error comes from OpenAI's rules for Chat Completions, and LaoZhang API now handles these requests on its side. If you still see it:

* Check that the base URL is `https://api.laozhang.ai/v1`, not OpenAI's or another provider's.
* Send support the time of the error, the model, and the full error message.

### Can GPT-6.1 Sol call tools without the Responses API?

Yes. On LaoZhang API, `gpt-6.1-sol` calls tools in Chat Completions, so clients and code that only support Chat Completions can use it.

### Does pricing change?

No. Billing is still per token at the model's rate. Tool definitions and function results count as input tokens, the call arguments the model returns count as output tokens, and there is no separate fee for tool calls.

### Should I move my Responses code back to Chat Completions?

No need; both work. If you stay on Responses, follow the [multi-turn pattern](https://docs.laozhang.ai/en/api-capabilities/function-calling.md#send-history-back-to-responses) when you send history back.

## Related documentation

* [Function calling](https://docs.laozhang.ai/en/api-capabilities/function-calling.md): full two-turn examples for Chat Completions and Responses
* [GPT-6 launch announcement](https://docs.laozhang.ai/en/announcements/gpt-6-launch-2026-09.md) and [GPT-6.1 Sol launch announcement](https://docs.laozhang.ai/en/announcements/gpt-6-1-sol-2026-10.md): prices, reasoning effort, and how to choose
* Setup guides for [Cline](https://docs.laozhang.ai/en/scenarios/programming/cline.md) and [Cherry Studio](https://docs.laozhang.ai/en/scenarios/chat/cherry-studio.md)
* OpenAI: [Function calling](https://developers.openai.com/api/docs/guides/function-calling), [Using GPT-6](https://developers.openai.com/api/docs/guides/latest-model)


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