OnlineOfficial specifications

Claude Fable 5.1

Anthropic · OpenAI-compatible API

claude-fable-5-1

Create account →Quickstart ↓

USD / 1M tokens

Input$5

Cache Read$0.125

Cache Write$6.25

Output$25

Context: 1M
Max Output: 128K
Tool Calling: ✓
Reasoning: ✓
Vision: ✓
Streaming: ✓

OpenAI-compatible API

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.iteracompute.com/v1",
    api_key=os.environ["ITERACOMPUTE_API_KEY"],
)
response = client.chat.completions.create(
    model="claude-fable-5-1",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(response.choices[0].message.content)

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.iteracompute.com/v1",
  apiKey: process.env.ITERACOMPUTE_API_KEY,
});
const response = await client.chat.completions.create({
  model: "claude-fable-5-1",
  messages: [{ role: "user", content: "Hello!" }],
});
console.log(response.choices[0].message.content);

curl https://api.iteracompute.com/v1/chat/completions \
  -H "Authorization: Bearer $ITERACOMPUTE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-fable-5-1",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

claude-fable-5-1View Docs →

Catalog updated: 2026-10-19.

Overview

Model for demanding reasoning and long-running agent work, with always-on adaptive thinking and image input.

Official model specifications

Context: 1M
Max Output: 128K
Tool calling: Supported
Reasoning: Supported
Image input: Supported
Streaming: Supported

Capabilities and full context are from provider documentation. Gateway request limits and feature availability can differ.

Model developer documentation · 2026-10-19

Adaptive thinking is always on for Opus, Fable and Mythos. Sonnet, Opus, Fable and Mythos reject forced tool choice; use automatic tool selection. Batch-only beta output limits are excluded here.

Gateway request limits

Input limit: 1,000,000
Output limit: 125K

A missing Gateway limit is unpublished, not unlimited. Provider capabilities are not a route acceptance test.

Tasks and selection tradeoffs

Use for code changes, document analysis and agent workflows. Validate tool handling and thinking controls on your selected interface before production use.

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Pricing

Prices in USD per 1M tokens.

Input$5

Cache Read$0.125

Cache Write$6.25

Output$25

Example task: Extract fields from a document

Assume 12,000 aggregate input tokens and 1,000 billable output tokens across all calls. No cache hit.

12,000 × $5 / 1M + 1,000 × $25 / 1M = $0.085000

If usage actually reports 9,000 of those input tokens as cached, replace that portion at the cached-input rate ($0.125/1M): $0.041125. Cached tokens are part of total input, never added on top.

Illustrative calculation using the 2026-10-19 catalog snapshot. Include every agent call and retry, repeated history and billable reasoning output; settle against actual usage and current Console prices.

Estimate your monthly cost

Uses the 2026-10-19 catalog snapshot, independently of the live prices above. USD per 1M tokens; an estimate, not a bill.

Estimate includes standard text input, cache reads and text output only. Long-context premiums, service tiers, cache writes, image output and tool fees are excluded.

Model

Input tokens / request

Billable output tokens / request

Cached share of input (%)

Requests / month

Input includes cached tokens; output includes billable reasoning. Count every API request, including agent steps and retries.

Estimated monthly cost

—USD / month

Claude Fable 5.1

Uncached input: —
Cache read: —
Billable output: —

Connect this model →

Calculation and billing basis

Monthly cost = requests × [input × (1 − cached share) × input rate + input × cached share × cache-read rate + output × output rate] / 1,000,000.

Cached tokens are part of total input, never added on top. Use actual cache-read hits from usage; repeating a prompt does not guarantee a hit. Missing rates are unconfirmed, not $0. Separate cache-write, storage and other additional fees are excluded. Settle against actual usage and current Console prices.

Enable JavaScript to use the calculator. The worked example above remains available.

Usage limits

Use the Gateway request limits above when configuring clients. Official context describes the model capacity, not an account entitlement.
Start with one representative task. Check correctness, actual usage and response time before increasing traffic.

API parameters

model: claude-fable-5-1
messages: [{"role": "user", "content": "Hello!"}]

Additional capabilities and model-specific parameters have not been verified on this route. Test required features before production use.

API

Base URL: https://api.iteracompute.com/v1
Endpoint: POST /v1/chat/completions
Model ID: claude-fable-5-1
Authentication: Authorization: Bearer ITERACOMPUTE_API_KEY

View Docs

FAQ

How do I use Claude Fable 5.1 with the OpenAI SDK?

Set base_url to https://api.iteracompute.com/v1 and model to claude-fable-5-1. Authenticate with your IteraCompute API key.

What does Claude Fable 5.1 cost?

See the pricing section for current input, cached-input and output rates in USD per 1M tokens. Check the refresh time before use.

What context length is available?

See the model specifications above for the current context and maximum output. Input and requested maximum output share the context budget.

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