---
title: "Claude Fable 5.1 — API access"
description: "Claude Fable 5.1 API pricing: official $10/$50 per 1M tokens, $5/$25 with the flat 50% apiToken.sale discount. Mythos-class with $0.25 cache reads."
url: "https://apitoken.sale/models/claude-fable-5-1"
language: "en"
---
# Claude Fable 5.1

Claude Fable 5.1 is Anthropic's current Mythos-class model — a tier above Opus for the longest-horizon agentic work, at double the Opus token price, with cache reads at $0.25 per 1M.

- **Model ID:** `claude-fable-5-1`
- **Tier:** Mythos
- **Context window:** 1M tokens
- **Max output:** 128K tokens
- **Official price (per 1M):** $10 input / $50 output
- **Your price (per 1M):** input $5, output $25 (flat 50% off)
- **Base URL:** `https://router.apitoken.sale` · **Endpoint:** `POST /v1/messages`

## Best for

- The longest-horizon autonomous runs where failure costs more than tokens.
- The hardest software tasks — the current Mythos GA.
- Cache-heavy agent loops that re-read a large prefix every turn.

## Notes

- Same $10/$50 tariff as Fable 5; cache reads are $0.25 per 1M (0.025× input) instead of Fable 5's $1.
- Adaptive thinking is always on; thinking tokens bill as output. Forced tool_choice any/tool is a 400.
- Safety classifiers may reroute sensitive requests to Opus. Mythos 5.1 stays Glasswing-only.

## Call it

```bash
curl https://router.apitoken.sale/v1/messages \
  -H "x-api-key: $APITOKEN_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{"model": "claude-fable-5-1", "max_tokens": 1024, "messages": [{"role": "user", "content": "Hello"}]}'
```

## FAQ

**How much does the Claude Fable 5.1 API cost?**

Officially $10 per 1M input tokens and $50 per 1M output tokens — the same as Fable 5. Cache reads are $0.25 per 1M (0.025× input). On apiToken.sale the flat 50% discount applies to every call: $5/$25, cache reads $0.125.

**What is the model ID for Claude Fable 5.1?**

claude-fable-5-1. Use it unchanged with the Anthropic SDK, Claude Code, Cursor or any compatible tool pointed at https://router.apitoken.sale.

**Fable 5.1 or Fable 5?**

Same input/output price. Fable 5.1 is the current GA, always-on adaptive thinking, and four times cheaper cache reads. New work should send claude-fable-5-1. Keep Fable 5 only when a toolchain is pinned to it.

---
API reference: https://apitoken.sale/md/docs · All models: https://apitoken.sale/md/models