Anthropic API

The Anthropic Messages protocol is supported natively. Point Claude Code, the Anthropic SDK, or any Anthropic-compatible client straight at the gateway.

Endpoint

POST https://api.eclogue.ai/v1/messages

Example request

{
  "model": "claude-sonnet-4-20250514",
  "max_tokens": 1024,
  "messages": [
    {"role": "user", "content": "What is the capital of France?"}
  ]
}

Required headers

Header	Value	Description
Authorization	Bearer gw-your-key	Your gateway API key
anthropic-version	2023-06-01	Anthropic API version (required)
Content-Type	application/json	Request body format

Parameters

Parameter	Type	Required	Description
model	string	Yes	Model ID (e.g. claude-sonnet-4-20250514)
messages	array	Yes	Array of conversation messages
max_tokens	integer	Yes	Maximum number of tokens to generate
system	string	No	System prompt (a top-level field, not part of messages)
stream	boolean	No	Enable SSE streaming
temperature	number	No	Sampling temperature (0–1)
tools	array	No	Tool definitions (function calling)
thinking	object	No	Extended thinking configuration

Example response

{
  "id": "msg_abc123",
  "type": "message",
  "role": "assistant",
  "model": "claude-sonnet-4-20250514",
  "content": [
    {"type": "text", "text": "The capital of France is Paris."}
  ],
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 15,
    "output_tokens": 9
  }
}

With curl

curl -X POST https://api.eclogue.ai/v1/messages \
  -H "Authorization: Bearer gw-your-key" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

With Python (Anthropic SDK)

import anthropic

client = anthropic.Anthropic(
    base_url="https://api.eclogue.ai",
    api_key="gw-your-key-here",
)

message = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello!"}],
)

print(message.content[0].text)

Streaming

Set "stream": true to receive Anthropic SSE events (message_start, content_block_delta, message_delta, message_stop):

curl -X POST https://api.eclogue.ai/v1/messages \
  -H "Authorization: Bearer gw-your-key" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 1024,
    "stream": true,
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

Configuring Claude Code

Set these environment variables in your shell to point Claude Code at the gateway:

# ~/.bashrc or ~/.zshrc
export ANTHROPIC_BASE_URL=https://api.eclogue.ai
export ANTHROPIC_AUTH_TOKEN=gw-your-key-here
export ANTHROPIC_API_KEY=""  # explicitly empty to prevent fallback

Claude Code will then send its requests to https://api.eclogue.ai/v1/messages.

Supported features

Every Anthropic feature is proxied through transparently:

• Extended thinking (the thinking parameter)
• Prompt caching (cache_control in messages)
• Tool use / function calling (the tools parameter)
• Vision (images in messages)
• PDF processing
• The anthropic-beta header for beta features

Differences from OpenAI Chat Completions

Aspect	OpenAI	Anthropic
Endpoint	/v1/chat/completions	/v1/messages
System prompt	Inside the messages array	Top-level system field
Token fields	prompt_tokens / completion_tokens	input_tokens / output_tokens
SSE format	data: ... + [DONE]	Typed events: message_start, content_block_delta, …
Required header	None	anthropic-version: 2023-06-01

Both protocols share the same API key, balance and billing. Pick whichever matches the SDK you already use.