Chat Completion (Anthropic native API)

1. Overview

Claude is Anthropic's large language model family, known for strong conversational, writing, coding, and reasoning capabilities. It handles long-context tasks well and is designed with a strong emphasis on safety.

2. Request

• Method:POST

• Endpoint:

  https://gateway.serevixai.ai/v1/messages
  

---

3. Parameters

3.1 Header Parameters

Parameter	Type	Required	Description	Example
Content-Type	string	Yes	Sets the request content type. It must be application/json	application/json
Accept	string	Yes	Sets the response content type. The recommended value is application/json	application/json
x-api-key	string	Yes	API key required for authentication, in the format $YOUR_API_KEY.	$YOUR_API_KEY

---

3.2 Body Parameters (application/json)

Parameter	Type	Required	Description	Example
model	string	Yes	The model ID to use. See Model List for available versions, such as claude-3-5-haiku-20241022.	claude-haiku-4-5-20251001
messages	array	Yes	A chat message list in the Anthropic native format. Each item contains role and content.	[{"role": "user","content": [{"type":"text","text":"Hello, tell me a joke."}]}]
message.role	string	No	Message role. Supported values: user and assistant.	user
message.content	array	No	The message content.	[{"type":"text","text":"Hello, tell me a joke."}]
system	array	No	System prompt content.	[{"type":"text","text":"You are a friendly AI assistant"}]
temperature	number	No	Sampling temperature in the range 0-2. Higher values make the output more random, while lower values make it more focused and deterministic.	0.7
top_p	number	No	Another way to control the sampling distribution, in the range 0-1. It is usually used instead of temperature.	0.9
stream	boolean	No	Whether to enable streaming output. When set to true, the API returns ChatGPT-style streamed data.	false
max_tokens	number	No	The maximum number of tokens that can be generated in a single reply, subject to the model context window.	8192

---

4. Request Examples

4.1 Chat

HTTPShellGoPython

POST /v1/messages
Content-Type: application/json
Accept: application/json
x-api-key: $YOUR_API_KEY

{
    "model": "claude-haiku-4-5-20251001",
    "max_tokens": 4096,
    "system": [{
        "type": "text",
        "text": "You are a friendly AI assistant"
    }],
    "messages": [{
        "role": "user",
        "content": [{
            "type": "text",
            "text": "Hello, can you explain quantum mechanics to me?"
        }]
    }]
}

curl https://gateway.serevixai.ai/v1/messages \
    -H "Content-Type: application/json" \
    -H "Accept: application/json" \
    -H "x-api-key: $YOUR_API_KEY" \
    -d "{
    \"model\": \"claude-haiku-4-5-20251001\",
    \"max_tokens\": 4096,
    \"system\": [{
        \"type\": \"text\",
        \"text\": \"You are a friendly AI assistant\"
    }],
    \"messages\": [{
        \"role\": \"user\",
        \"content\": [{
            \"type\": \"text\",
            \"text\": \"Hello, can you explain quantum mechanics to me?\"
        }]
    }]
}"

package main

import (
    "context"
    "fmt"

    "github.com/anthropics/anthropic-sdk-go"
    "github.com/anthropics/anthropic-sdk-go/option"
)

func main() {
    apiKey := "sk-123456789012345678901234567890123456789012345678"

    client := anthropic.NewClient(
        option.WithAPIKey(apiKey),
        option.WithBaseURL("https://gateway.serevixai.ai"),
    )

    resp, err := client.Messages.New(
        context.Background(),
        anthropic.MessageNewParams{
            Model:     "claude-haiku-4-5-20251001",
            MaxTokens: 4096,
            System: []anthropic.TextBlockParam{
                {
                    Type: "text",
                    Text: "You are a friendly AI assistant",
                },
            },
            Messages: []anthropic.MessageParam{
                anthropic.NewUserMessage(anthropic.NewTextBlock("Hello, can you explain quantum mechanics to me?")),
            },
        },
    )

    if err != nil {
        fmt.Println("error:", err)
        return
    }

    for _, block := range resp.Content {
        if block.Type == "text" {
            fmt.Println("💬 Assistant reply:")
            fmt.Println(block.Text)
        }
    }

    fmt.Println("\n📊 Token usage:")
    fmt.Printf("  - Input tokens: %d\n", resp.Usage.InputTokens)
    fmt.Printf("  - Output tokens: %d\n", resp.Usage.OutputTokens)
}

#!/usr/bin/env python3

from anthropic import Anthropic

def main():
    api_key = "sk-123456789012345678901234567890123456789012345678"

    client = Anthropic(
        api_key=api_key,
        base_url="https://gateway.serevixai.ai"
    )

    response = client.messages.create(
        model="claude-haiku-4-5-20251001",
        max_tokens=4096,
        system=[{
            "type": "text",
            "text": "You are a friendly AI assistant"
        }],
        messages=[{
            "role": "user",
            "content": "Hello, can you explain quantum mechanics to me?"
        }]
    )

    for block in response.content:
        if block.type == "text":
            print("💬 Assistant reply:")
            print(block.text)

    print("\n📊 Token usage:")
    print(f"  - Input tokens: {response.usage.input_tokens}")
    print(f"  - Output tokens: {response.usage.output_tokens}")

if __name__ == "__main__":
    main()

5. Response Example

{
    "model": "claude-3-5-haiku-20241022",
    "id": "msg_bdrk_01AZpXbu4crT5R6gsYJwk6KD",
    "type": "message",
    "role": "assistant",
    "content": [{
        "type": "text",
        "text": "Quantum mechanics is the branch of physics that studies the microscopic world..."
    }],
    "stop_reason": "end_turn",
    "stop_sequence": null,
    "usage": {
        "input_tokens": 36,
        "cache_creation_input_tokens": 0,
        "cache_read_input_tokens": 0,
        "output_tokens": 366
    }
}