Claude Fable 5

by Anthropic

anthropic/claude-fable-5

A Mythos-class model for demanding reasoning and long-running autonomous work, with always-on adaptive thinking.

Modalities
Text, Image
In / out per 1M
$10 / $50
Context
1M
Released
Jun 9, 2026

Overview

A Mythos-class model for demanding reasoning and long-running autonomous work, with always-on adaptive thinking. It is billed from the same balance as every other model and API here, and the price of each call comes back in the response.

Pricing

The default plan, in USD per million tokens.

MeterPer 1M tokens
Input$10.00
Output$50.00
Cache read$1.00
Cache write$12.50

Your balance and per-call records come from /v1/credits and /v1/generation.

Use it

Point your client at the gateway and pass this model id. Nothing else changes.

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
  baseURL: "https://gateway.agentsky.dev",
  apiKey: process.env.AGENTSKY_API_KEY, // ast_…
});

const message = await client.messages.create({
  model: "anthropic/claude-fable-5",
  max_tokens: 256,
  messages: [{ role: "user", content: "Summarise this ticket." }],
});
console.log(message.usage.cost); // USD, in the response

Questions

Claude Fable 5 — AgentSky