Short answer
As of November 2, 2026, Anthropic has not released Claude Fable 5.5 and has not announced a release date. The newest Fable is Claude Fable 5.1, released on September 1, 2026, with the model ID claude-fable-5-1; Anthropic's models overview lists no Fable 5.5. Anthropic's list price for Fable 5.1 is $10 per million input tokens and $50 per million output tokens, and the live Moyi API price is on the model page. In Claude Code, set ANTHROPIC_MODEL=claude-fable-5-1.
To follow its launch on Moyi API, or vote for it, see the Claude Fable 5.5 API page.
What Claude Fable is
Fable is Anthropic's top model line, above Opus. It is the choice when reasoning quality matters most: architecture decisions, large unfamiliar codebases, long agent runs that simpler models don't finish. The current version, Fable 5.1, has a 1M-token context window, up to 128K output tokens, adaptive thinking that is always on (default effort high), and a reliable knowledge cutoff of June 2026.
Fable 5.1 vs Opus 5.5, Sonnet 5.5 and Haiku 5.5
| Model | Model ID | Anthropic list price, input / output per 1M | Use it for |
|---|---|---|---|
| Fable 5.1 | claude-fable-5-1 |
$10 / $50 | The hardest tasks |
| Opus 5.5 | claude-opus-5-5 |
$4 / $20 | Hard coding work |
| Sonnet 5.5 | claude-sonnet-5-5 |
$2 / $10 | Everyday development |
| Haiku 5.5 | claude-haiku-5-5 |
from $0.10 / $0.50 | Background chores and subagents |
Anthropic's own advice is to start with Opus 5.5 for most workloads and move to Fable 5.1 for demanding reasoning and long agent runs, or when Opus 5.5 at higher effort still falls short. A practical setup: work on Sonnet 5.5 or Opus 5.5 and switch to Fable 5.1 only for the hard steps, so most tokens are billed at the cheaper model's price.
How much Fable 5.1 costs
Anthropic list price per 1 million tokens, in USD:
| Fable 5.1 | |
|---|---|
| Input | $10 |
| Output | $50 |
| Cache write, 5 minutes / 1 hour | $12.50 / $20 |
| Cache read | $0.25 |
The live Moyi API price is on the model page. You pay only for tokens used, with no subscription. More detail: Claude Fable 5.1 pricing.
What that looks like: a typical Claude Code session on a mid-sized project reads about 200k input tokens and writes 20k output tokens, which is about $3 at Fable 5.1's list price before caching. For a full cost comparison, see Claude subscription vs API pay-per-use.
Claude Code: Fable 5.1 as the main model
New accounts start with a $0 balance — top up before your first request. Top up from $5. If a request returns 402 with "wallet balance is insufficient", your balance is empty — your base URL and key are fine. Top up and retry.
Create a Moyi API API key in the console. If Claude Code isn't installed yet, start with the install guide.
macOS and Linux — add to ~/.zshrc (or ~/.bashrc):
export ANTHROPIC_BASE_URL=https://api.moyi-api.com
export ANTHROPIC_AUTH_TOKEN="your Moyi API key"
export ANTHROPIC_MODEL=claude-fable-5-1
Windows (PowerShell):
setx ANTHROPIC_BASE_URL "https://api.moyi-api.com"
setx ANTHROPIC_AUTH_TOKEN "your Moyi API key"
setx ANTHROPIC_MODEL "claude-fable-5-1"
Then reopen the terminal and run claude.
To keep Sonnet 5.5 as your main model and use Fable 5.1 for a single session:
claude --model claude-fable-5-1
If Claude Code says it doesn't recognize the model, run claude update.
Calling the API directly
Anthropic format:
curl https://api.moyi-api.com/v1/messages \
-H "x-api-key: YOUR_KEY" \
-H "anthropic-version: 2023-06-01" \
-H "content-type: application/json" \
-d '{
"model": "claude-fable-5-1",
"max_tokens": 2048,
"messages": [{"role": "user", "content": "Design an architecture for a message queue service and explain the trade-offs"}]
}'
OpenAI-compatible format:
from openai import OpenAI
client = OpenAI(base_url="https://api.moyi-api.com/v1", api_key="YOUR_KEY")
resp = client.chat.completions.create(
model="claude-fable-5-1",
messages=[{"role": "user", "content": "Find the cause of the data race in this code: ..."}],
)
print(resp.choices[0].message.content)
Full parameter reference: API integration.
Paying for usage
You top up a balance in the console and are charged only for tokens actually used — no subscription. The minimum top-up is $5.
- Card — Visa, Mastercard and other major cards via Stripe.
FAQ
Is Claude Fable 5.5 out? No. As of November 2, 2026, Anthropic has not released Fable 5.5 or announced a date. The latest Fable is Fable 5.1 (claude-fable-5-1), released September 1, 2026.
Which model ID should I use? claude-fable-5-1. There is no claude-fable-5-5 model, so requests that use that name won't work.
How much does Claude Fable 5.1 cost? $10 per million input tokens and $50 per million output tokens at Anthropic's list price. The live Moyi API price is on the model page.
Fable 5.1 or Opus 5.5? Fable 5.1 costs 2.5x as much per token, so keep it for tasks Opus 5.5 doesn't get right. For most coding work, Opus 5.5 or Sonnet 5.5 is enough.
Do I need an Anthropic account? No. A Moyi API key is enough.