Anthropic: Claude Fable 5

Claude Fable 5 is Anthropic’s generally available Mythos-class model for autonomous knowledge work, advanced reasoning, and long-horizon coding. It supports text, image, and file inputs with text output, a 1M-token context window, always-on adaptive thinking, tool use, and structured outputs.

Why It Looks Great

• Anthropic’s most capable widely released model for demanding reasoning and long-horizon agentic work
• Mythos-class capability made generally available with robust public-release safeguards
• 1M-token context window for large codebases, long documents, research corpora, and extended multi-turn workflows
• Up to 128K output tokens for long-form reasoning, coding, analysis, and structured generation
• Strong fit for autonomous software engineering, enterprise knowledge work, scientific analysis, and complex planning
• Vision and file input support for screenshots, diagrams, PDFs, documents, and multimodal analysis
• Always-on adaptive thinking for deeper reasoning without manual thinking-mode configuration
• Function calling and tool-use support for agentic application workflows
• Structured output support for JSON responses and schema-constrained generation

Key Features

• Context Window: 1,000,000 tokens
• Max Input: 872,000 tokens
• Max Output: 128,000 tokens
• Input: Text, Image, File
• Output: Text
• Vision: Supported
• File Input: Supported
• Function Calling: Supported
• Structured Outputs: Supported
• Adaptive Thinking: Supported, always on
• Image Generation: Not listed
• Audio Input: Not listed
• Supported Parameters: include_reasoning, max_completion_tokens, max_tokens, reasoning, response_format, stop, structured_outputs, tool_choice, tools, verbosity

Specifications

How to Use

1. Write your prompt - describe the task, provide context, and specify the desired output format.
2. Submit - the model processes your request and returns the response.

API Integration

Base URL: https://llm.wavespeed.ai/v1
API Endpoint: chat/completions
Model ID: anthropic/claude-fable-5

API Usage

Python SDK

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://llm.wavespeed.ai/v1"
)

response = client.chat.completions.create(
    model="anthropic/claude-fable-5",
    messages=[{"role": "user", "content": "Hello!"}]
)

print(response.choices[0].message.content)

cURL

curl https://llm.wavespeed.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "anthropic/claude-fable-5",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

Notes

• Model: anthropic/claude-fable-5
• Provider: anthropic
• Best suited for autonomous knowledge work, long-horizon coding, complex reasoning, enterprise research, multimodal document analysis, and high-autonomy tool workflows
• Robust safeguards apply for high-risk domains; some sensitive requests may be refused or routed to a safer fallback model