Claude Fable 5 Economy

Claude Fable 5 is Anthropic’s officially released Mythos-tier model, designed for autonomous knowledge work, advanced reasoning, and long-horizon coding. It supports text, image, and file inputs and produces text output. It features a 1-million-token context window, up to 128,000 output tokens, and built-in always-on adaptive thinking, tool use, and structured outputs. The model shares the same underlying model family as Claude Mythos 5 but was released publicly with stronger safety safeguards. It is suitable for complex software engineering, multi-step agentic workflows, enterprise research, document analysis, and professional tasks requiring sustained reasoning and high reliability.

Claude Fable 5 Economy

Base URL

https://api.icreat.ai

Model Code

claude-fable-5

Authentication

All API requests must be authenticated with an API Key. You can obtain an API Key from the console.

export ICREAT_API_KEY="your-api-key-here"

HTTP Request Headers

import os

API_KEY = os.environ.get("ICREAT_API_KEY")
headers = {
    "Content-Type": "application/json",
    "Authorization": "Bearer " + API_KEY,
}

Protect your API Key

Never expose your API Key in client-side code or public repositories. Use environment variables or a backend proxy.

Code Examples

This model is invoked via the Anthropic-compatible Messages API, supporting streaming and non-streaming modes.

POST/v1/messages

curl --fail-with-body --connect-timeout 10 --max-time 60 \
  -X POST https://api.icreat.ai/v1/messages \
  -H "Authorization: Bearer ${ICREAT_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "claude-fable-5",
  "messages": [
    {"role": "system", "content": "You are a helpful assistant."},
    {"role": "user", "content": "Which is healthier, coffee or tea?"}
  ],
  "stream": false
}'

Input Schema

Total: 4 Required: 2 Optional: 2

modelstringrequired

Model ID. Must be iCreat model_code (claude-fable-5).

messagesarray[object]required

Conversation messages.

max_tokensinteger

Maximum tokens to generate.

streamboolean

Whether to stream the response.

Output Schema

Anthropic Messages compatible response.

Total: 4

idstring

Message ID.

typestring

Object type, always message.

rolestring

Role, always assistant.

contentarray[object]

Content blocks from the model.

LLM-friendly prompt

Below is an LLM-friendly Markdown prompt you can copy into Cursor, ChatGPT, or other AI assistants to help them understand this model's API integration, call flow, and key parameters.

# claude-fable-5

> Claude Fable 5 is Anthropic’s officially released Mythos-tier model, designed for autonomous knowledge work, advanced reasoning, and long-horizon coding.

## Overview

Call via iCreat Anthropic-compatible Messages API; supports streaming and non-streaming.

## API Info

- **Base URL**: `https://api.icreat.ai`
- **Endpoint (POST)**: `/v1/messages`
- **Model ID**: `claude-fable-5`
- **Auth**: `Authorization: Bearer ${ICREAT_API_KEY}`

## Call Flow

Single POST; `stream: false` returns full JSON, `stream: true` streams via SSE.

### Input

- `model` (required): iCreat model_code `claude-fable-5`
- `messages` (required): conversation messages
- Common optional: `max_tokens`, `stream`

### Output

- Read reply from `content` text blocks (e.g. `content[0].text`)

## Notes

- `model` must be the iCreat model_code
- Other fields follow the Anthropic Messages protocol