GPT-5.1 Codex Max

GPT-5.1 Codex Max is a coding and software engineering model from OpenAI. Call gpt-5.1-codex-max through MixRoute using the endpoint shown below.

Key capabilities

Responses API - Uses input for text and structured content
Reasoning control - Configure reasoning effort on supported models
Tool use - Supports function and hosted tool definitions

Quick example

cURL
Python
Streaming

curl "https://api.mixroute.ai/v1/responses" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "gpt-5.1-codex-max",
  "input": [
    {
      "role": "user",
      "content": "Explain quantum entanglement in simple terms."
    }
  ],
  "max_output_tokens": 256,
  "reasoning": {
    "effort": "low"
  }
}'

from openai import OpenAI

client = OpenAI(api_key="YOUR_API_KEY", base_url="https://api.mixroute.ai/v1")

response = client.responses.create(
    model="gpt-5.1-codex-max",
    input="Explain quantum entanglement in simple terms.",
    reasoning={"effort": "low"},
    max_output_tokens=256,
)

print(response.output_text)

from openai import OpenAI

client = OpenAI(api_key="YOUR_API_KEY", base_url="https://api.mixroute.ai/v1")

with client.responses.stream(
    model="gpt-5.1-codex-max",
    input="Write a short poem about the sea.",
    reasoning={"effort": "low"},
    max_output_tokens=256,
) as stream:
    for event in stream:
        if event.type == "response.output_text.delta":
            print(event.delta, end="")

Parameters

Parameter	Type	Required	Description
`model`	string	Yes	Must be `gpt-5.1-codex-max`.
`input`	string \| array	Yes	Text or structured response input.
`max_output_tokens`	integer	No	Maximum output tokens.
`stream`	boolean	No	Enable SSE streaming. Default: false.
`reasoning`	object	No	Reasoning configuration, including effort.
`text`	object	No	Text format and verbosity controls.
`tools`	array	No	Tools the model may call.
`store`	boolean	No	Whether to store the response.

Home

Model Introduction

Key capabilities

Quick example

Parameters

​Key capabilities

​Quick example

​Parameters

Key capabilities

Quick example

Parameters