claude-opus-4-8 - Create Chat Completion (AI Model · By )

API Documentation

API Reference

Chat

Create Chat Completion

Supported Model Code

Loading models...

claude-opus-4-8

claude-opus-4-80 models support this endpoint

Claude Opus 4.8 is Anthropic's most capable generally available model in the Opus family. It supports text, image, and file inputs with text output, featuring reasoning capabilities and a 1M-token context window. It is ideally suited for highly autonomous agents, long-horizon agentic work, knowledge work, and memory-driven tasks where coherence over extended sessions is critical. The model excels particularly at multi-step reasoning, complex coding, and end-to-end project orchestration—handling large codebases, multi-stage debugging, and long-running asynchronous agent pipelines. Beyond coding, it manages knowledge work such as drafting documents, building presentations, and analyzing data, consistently maintaining high quality across very long outputs.

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...

temperature?number

Higher values make output more random, lower more deterministic.

Example Value: 1Value Range: 0 ≤ value ≤ 1step: 0.1

top_p?number

Nucleus sampling threshold; an alternative to temperature.

Example Value: 1Value Range: 0 ≤ value ≤ 1step: 0.05

max_tokens?number

Example Value: 4096Value Range: 1 ≤ value ≤ 65536

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": "claude-opus-4-8",
  "messages": [
    {
      "role": "system",
      "content": "You are a senior software architect."
    },
    {
      "role": "user",
      "content": "Explain the trade-offs between microservices and a monolith."
    }
  ],
  "temperature": 0.7,
  "top_p": 1,
  "max_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...

claude-opus-4-8

claude-opus-4-80 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...

temperature?number

Higher values make output more random, lower more deterministic.

Example Value: 1Value Range: 0 ≤ value ≤ 1step: 0.1

top_p?number

Nucleus sampling threshold; an alternative to temperature.

Example Value: 1Value Range: 0 ≤ value ≤ 1step: 0.05

max_tokens?number

Example Value: 4096Value Range: 1 ≤ value ≤ 65536

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": "claude-opus-4-8",
  "messages": [
    {
      "role": "system",
      "content": "You are a senior software architect."
    },
    {
      "role": "user",
      "content": "Explain the trade-offs between microservices and a monolith."
    }
  ],
  "temperature": 0.7,
  "top_p": 1,
  "max_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"
}