GPT-5 - Create Chat Completion (AI Model · By )

API Documentation

API Reference

Chat

Create Chat Completion

Supported Model Code

Loading models...

GPT-5 (gpt-5)

gpt-50 models support this endpoint

GPT-5 is an intelligent reasoning model from OpenAI, designed for coding, reasoning, and agentic tasks across domains. It supports text and image inputs with text output, a 400,000-token context window, and up to 128,000 output tokens. With configurable reasoning effort, reasoning token support, streaming, function calling, Structured Outputs, and hosted tools such as web search, file search, image generation, code interpreter, and MCP, GPT-5 is well-suited for software engineering, complex reasoning, tool-based workflows, long-context applications, autonomous agents, and production-grade AI assistants.

Create chat completion

https://api.modelstream.ai

POST/v1/chat/completions

Authentication

BearerAuth

AuthenticationBearer <token>

All API requests must be authenticated using a Bearer token in the Authorization header. Please ensure your API key is active.Authorization: Bearer sk-xxxxxx

Parameter Location: Header Param

Request Body

application/json

These parameters come from the selected model form_schema. Switching models updates this list and the request example.

system_prompt?string

Global instructions or persona for the model.

Example Value: You are a helpful and expert assistant.Placeholder: e.g., You are a senior software architect...

prompt*string

RequiredExample Value: Hello! What can you do?Placeholder: Enter your question or instructions...

image_urls?array

Supports multi-image understanding (optional).

Value Range: 0 ≤ value ≤ 10

image_detail?string

Example Value: auto

Enum/Options:

Auto: autoLow: lowHigh: high

reasoning_effort?string

Controls how much reasoning effort the model spends before answering.

Example Value: medium

Enum/Options:

Minimal: minimalLow: lowMedium: mediumHigh: high

verbosity?string

Controls how verbose the response is.

Example Value: medium

Enum/Options:

Low: lowMedium: mediumHigh: high

max_completion_tokens?number

Example Value: 8192Value Range: 1 ≤ value ≤ 128000

response_format?string

Example Value: text

Enum/Options:

Text: textJSON Object: json_object

stream?boolean

Example Value: true

Response Parameters

application/json

200apiDocs.responses.successCreateResponse

id?string

Parameter description for Id

object?string

Parameter description for Object

created?integer

Parameter description for Created

model?string

Model ID used

choices?array

Parameter description for Choices

usage?object

Parameter description for Usage

prompt_tokens?integer

Parameter description for Prompt Tokens

completion_tokens?integer

Parameter description for Completion Tokens

total_tokens?integer

Parameter description for Total Tokens

prompt_tokens_details?object

Parameter description for Prompt Tokens Details

completion_tokens_details?object

Parameter description for Completion Tokens Details

system_fingerprint?string

Parameter description for System Fingerprint

400apiDocs.responses.badRequestParams

error?object

Parameter description for Error

message?string

Error Message

type?string

Error Type

param?string

Related Parameters

code?string

Error Code

429apiDocs.responses.rateLimited

error?object

Parameter description for Error

message?string

Error Message

type?string

Error Type

param?string

Related Parameters

code?string

Error Code

curl -X POST "https://api.modelstream.ai/v1/chat/completions" \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "gpt-5",
  "messages": [
    {
      "role": "developer",
      "content": "You are a senior software architect."
    },
    {
      "role": "user",
      "content": [
        {
          "type": "text",
          "text": "Analyze this diagram and suggest improvements for scalability."
        },
        {
          "type": "image_url",
          "image_url": {
            "url": "https://example.com/arch.png",
            "detail": "high"
          }
        }
      ]
    }
  ],
  "reasoning_effort": "high",
  "verbosity": "medium",
  "max_completion_tokens": 4096,
  "stream": true
}'

{
  "id": "string",
  "object": "chat.completion",
  "created": 0,
  "model": "string",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "system",
        "content": null,
        "name": "string",
        "tool_calls": [
          {
            "id": "string",
            "type": "function",
            "function": {
              "name": "string",
              "arguments": "string"
            }
          }
        ],
        "tool_call_id": "string",
        "reasoning_content": "string"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 0,
    "completion_tokens": 0,
    "total_tokens": 0,
    "prompt_tokens_details": {
      "cached_tokens": 0,
      "text_tokens": 0,
      "audio_tokens": 0,
      "image_tokens": 0
    },
    "completion_tokens_details": {
      "text_tokens": 0,
      "audio_tokens": 0,
      "reasoning_tokens": 0
    }
  },
  "system_fingerprint": "string"
}

API Documentation

API Reference

Chat

Create Chat Completion

Supported Model Code

Loading models...

GPT-5 (gpt-5)

gpt-50 models support this endpoint

Create chat completion

https://api.modelstream.ai

POST/v1/chat/completions

Authentication

BearerAuth

AuthenticationBearer <token>

All API requests must be authenticated using a Bearer token in the Authorization header. Please ensure your API key is active.Authorization: Bearer sk-xxxxxx

Parameter Location: Header Param

Request Body

application/json

These parameters come from the selected model form_schema. Switching models updates this list and the request example.

system_prompt?string

Global instructions or persona for the model.

Example Value: You are a helpful and expert assistant.Placeholder: e.g., You are a senior software architect...

prompt*string

RequiredExample Value: Hello! What can you do?Placeholder: Enter your question or instructions...

image_urls?array

Supports multi-image understanding (optional).

Value Range: 0 ≤ value ≤ 10

image_detail?string

Example Value: auto

Enum/Options:

Auto: autoLow: lowHigh: high

reasoning_effort?string

Controls how much reasoning effort the model spends before answering.

Example Value: medium

Enum/Options:

Minimal: minimalLow: lowMedium: mediumHigh: high

verbosity?string

Controls how verbose the response is.

Example Value: medium

Enum/Options:

Low: lowMedium: mediumHigh: high

max_completion_tokens?number

Example Value: 8192Value Range: 1 ≤ value ≤ 128000

response_format?string

Example Value: text

Enum/Options:

Text: textJSON Object: json_object

stream?boolean

Example Value: true

Response Parameters

application/json

200apiDocs.responses.successCreateResponse

id?string

Parameter description for Id

object?string

Parameter description for Object

created?integer

Parameter description for Created

model?string

Model ID used

choices?array

Parameter description for Choices

usage?object

Parameter description for Usage

prompt_tokens?integer

Parameter description for Prompt Tokens

completion_tokens?integer

Parameter description for Completion Tokens

total_tokens?integer

Parameter description for Total Tokens

prompt_tokens_details?object

Parameter description for Prompt Tokens Details

completion_tokens_details?object

Parameter description for Completion Tokens Details

system_fingerprint?string

Parameter description for System Fingerprint

400apiDocs.responses.badRequestParams

error?object

Parameter description for Error

message?string

Error Message

type?string

Error Type

param?string

Related Parameters

code?string

Error Code

429apiDocs.responses.rateLimited

error?object

Parameter description for Error

message?string

Error Message

type?string

Error Type

param?string

Related Parameters

code?string

Error Code

curl -X POST "https://api.modelstream.ai/v1/chat/completions" \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "gpt-5",
  "messages": [
    {
      "role": "developer",
      "content": "You are a senior software architect."
    },
    {
      "role": "user",
      "content": [
        {
          "type": "text",
          "text": "Analyze this diagram and suggest improvements for scalability."
        },
        {
          "type": "image_url",
          "image_url": {
            "url": "https://example.com/arch.png",
            "detail": "high"
          }
        }
      ]
    }
  ],
  "reasoning_effort": "high",
  "verbosity": "medium",
  "max_completion_tokens": 4096,
  "stream": true
}'

{
  "id": "string",
  "object": "chat.completion",
  "created": 0,
  "model": "string",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "system",
        "content": null,
        "name": "string",
        "tool_calls": [
          {
            "id": "string",
            "type": "function",
            "function": {
              "name": "string",
              "arguments": "string"
            }
          }
        ],
        "tool_call_id": "string",
        "reasoning_content": "string"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 0,
    "completion_tokens": 0,
    "total_tokens": 0,
    "prompt_tokens_details": {
      "cached_tokens": 0,
      "text_tokens": 0,
      "audio_tokens": 0,
      "image_tokens": 0
    },
    "completion_tokens_details": {
      "text_tokens": 0,
      "audio_tokens": 0,
      "reasoning_tokens": 0
    }
  },
  "system_fingerprint": "string"
}

GPT-5 - Create Chat Completion (AI Model · By ) | ModelStream