Create message (Anthropic)

POSThttps://api.poe.com/v1/messages

Overview

Creates a message using the Anthropic Messages API format. This endpoint provides a drop-in replacement for the Anthropic API, allowing you to use your Poe subscription points to access Claude models.

⚠️ Claude Models Only: This endpoint only supports official Anthropic Claude models. You cannot use this endpoint to call custom bots or models from other providers. For access to all bots on Poe, use the OpenAI-compatible API or the Poe Python SDK.

Key benefits:

Drop-in replacement for Anthropic API
Works with existing Anthropic SDK code
Use your existing Poe subscription points
No separate Anthropic API key needed
Requests proxied directly to provider with minimal transformation

Features:

Streaming support via SSE
Tool calling (function calling)
Multi-modal inputs (text, images)
Vision capabilities

Authentication

Send your Poe API key in the Authorization header:

Authorization: Bearer sk_test_51SAMPLEKEY

All requests must be made over HTTPS.

Parameters

Name	Location	Type	Required	Description
`anthropic-version`	header	string	Required	Anthropic API version (required)

Request body

Field	Type	Required	Description
`model`	string	Required	Claude model to use. You can use either Poe bot names or Anthropic API model names. Supported models: - `claude-sonnet-4`, `claude-sonnet-4-20250514` - `claude-opus-4`, `claude-opus-4-20250514` - `claude-sonnet-4.5`, `claude-sonnet-4-5-20250929` - `claude-opus-4.5`, `claude-opus-4-5-20251101` - `claude-haiku-3.5`, `claude-3-5-haiku-20241022` - And other Claude models available on Poe
`max_tokens`	integer	Required	Maximum number of tokens to generate
`messages`	object[]	Required	A list of messages comprising the conversation
`messages[].role`	"user" \| "assistant"	Required	The role of the message author Allowed values: `user`, `assistant`
`messages[].content`	string \| object[]	Required	The contents of the message
`system`	string \| object[]	Optional	System prompt for the conversation
`temperature`	number	Optional	Sampling temperature between 0 and 1 Min: 0 · Max: 1
`top_p`	number	Optional	Nucleus sampling parameter
`top_k`	integer	Optional	Top-k sampling parameter
`stream`	boolean	Optional	Whether to stream the response Default: `false`
`stop_sequences`	string[]	Optional	Custom sequences that will cause the model to stop
`tools`	object[]	Optional	Definitions of tools the model may use
`tool_choice`	object	Optional	How the model should use the provided tools
`metadata`	object	Optional	Metadata about the request

Responses

Field	Type	Required	Description
`id`	string	Optional	Unique identifier for the message
`type`	"message"	Optional	Object type, always "message" Allowed values: `message`
`role`	"assistant"	Optional	Role of the generated message Allowed values: `assistant`
`content`	object[]	Optional	Array of content blocks
`content[].type`	"text" \| "tool_use"	Optional	Type of content block Allowed values: `text`, `tool_use`
`content[].text`	string	Optional	Text content (for text blocks)
`content[].id`	string	Optional	Tool use ID (for tool_use blocks)
`content[].name`	string	Optional	Tool name (for tool_use blocks)
`content[].input`	object	Optional	Tool input (for tool_use blocks)
`model`	string	Optional	The model that handled the request
`stop_reason`	"end_turn" \| "max_tokens" \| "stop_sequence" \| "tool_use"	Optional	Reason the model stopped generating Allowed values: `end_turn`, `max_tokens`, `stop_sequence`, `tool_use`
`stop_sequence`	string \| null	Optional	The stop sequence that caused generation to stop, if any
`usage`	object	Optional
`usage.input_tokens`	integer	Optional	Number of input tokens
`usage.output_tokens`	integer	Optional	Number of output tokens

❌ Error codes

Http	Type	Description
400	`invalid_request_error`	Invalid request Malformed request or missing required fields
401	`authentication_error`	Authentication failed Invalid API key
404	`not_found_error`	Model not found Requested model not found. Only Claude models are supported.
429	`rate_limit_error`	Rate limit exceeded Rate limit exceeded (500 requests per minute)

🔁 Callbacks & webhooks

No callbacks or webhooks are associated with this endpoint.

Code example

Code example for this endpoint.

curl https://api.poe.com/v1/messages \
-X POST \
-H "Authorization: Bearer sk_test_51SAMPLEKEY" \
-H "Accept: application/json" \
-H "Content-Type: application/json" \
-d '{
  "model": "claude-sonnet-4",
  "max_tokens": 1024,
  "messages": [
    {
      "role": "user",
      "content": "What are the top 3 things to do in New York?"
    }
  ]
}'

Normal response

{
"id": "req_poe_63390c6692a844208526755996734287",
"type": "message",
"role": "assistant",
"content": [
  {
    "type": "text",
    "text": "Here are the top 3 things to do in New York:\n\n1. Visit Central Park\n2. See the Statue of Liberty\n3. Experience Times Square"
  }
],
"model": "claude-sonnet-4-20250514",
"stop_reason": "end_turn",
"stop_sequence": null,
"usage": {
  "input_tokens": 15,
  "output_tokens": 45
}
}

Streaming response

event: message_start
data: {"type":"message_start","message":{"id":"req_poe_63390c6692a844208526755996734287","type":"message","role":"assistant","content":[],"model":"claude-sonnet-4-20250514","stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":15,"output_tokens":0}}}

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Here"}}

event: message_stop
data: {"type":"message_stop"}