LLM Reference
Vercel AI Gateway

Using Claude Fable 5 on Vercel AI Gateway

Implementation guide · Claude Fable · Anthropic

Serverless

Quick Start

  1. 1
    Create an account at Vercel AI Gateway and generate an API key.
  2. 2
    Use the Vercel AI Gateway SDK or REST API to call anthropic/claude-fable-5 — see the documentation for request format.
  3. 3
    You'll be billed $10.00/1M input, $50.00/1M output tokens. See full pricing.

Code Examples

Install
pip install openai
API key
AI_GATEWAY_API_KEY
Model ID
anthropic/claude-fable-5

creator/model-name e.g. kwaipilot/kat-coder-pro-v2

import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["AI_GATEWAY_API_KEY"],
    base_url="https://ai-gateway.vercel.sh/v1"
)
response = client.chat.completions.create(
    model="anthropic/claude-fable-5",
    messages=[{"role": "user", "content": "Hello"}]
)
print(response.choices[0].message.content)

About Vercel AI Gateway

Vercel AI Gateway is a unified AI proxy providing a single OpenAI-compatible API endpoint to 275+ models from 25+ providers including Anthropic, OpenAI, Google, Meta, Mistral, DeepSeek, xAI, Alibaba, Amazon, ByteDance, Cohere, MiniMax, MoonshotAI, KwaiPilot, Black Forest Labs, Recraft, Voyage AI, NVIDIA, and more. Pricing is pass-through at provider list rates with zero markup. Includes $5/month free tier; paid is pay-as-you-go. Features: automatic provider fallbacks, unified observability, streaming, tool use, vision, embeddings, image/video generation, BYOK mode. Integrates via @ai-sdk/gateway package or plain model ID strings in Vercel AI SDK. API details: API key via Authorization: Bearer <AI_GATEWAY_API_KEY>. Key from Vercel dashboard. Free $5/month credit; paid tier is provider list price with zero markup. BYOK (bring-your-own-key) also supported with no markup or fee. Model IDs use {provider-owner}/{model-name} — e.g., anthropic/claude-opus-4.6, openai/gpt-5.

Vercel AI Gateway is a unified AI proxy providing a single OpenAI-compatible API endpoint to 275+ models from 25+ providers including Anthropic, OpenAI, Google, Meta, Mistral, DeepSeek, xAI, Alibaba, Amazon, ByteDance, Cohere, MiniMax, MoonshotAI, KwaiPilot, Black Forest Labs, Recraft, Voyage AI, NVIDIA, and more. Pricing is pass-through at provider list rates with zero markup. Includes $5/month free tier; paid is pay-as-you-go. Features: automatic provider fallbacks, unified observability, streaming, tool use, vision, embeddings, image/video generation, BYOK mode. Integrates via @ai-sdk/gateway package or plain model ID strings in Vercel AI SDK.

Pricing on Vercel AI Gateway

TypePrice (per 1M)
Input tokens$10.00
Output tokens$50.00

Capabilities

VisionMultimodalReasoningFunction CallingTool UseStructured OutputsPrompt CachingBatch API

About Claude Fable 5

Anthropic's most capable widely released model, built for demanding reasoning and long-horizon agentic work. Claude Fable 5 is the generally available Mythos-class Claude model, supports vision, tool use, structured outputs, prompt caching, Batch API processing, adaptive thinking that is always on, a 1M-token context window, and up to 128k output tokens. It launched on the Claude API, AWS Bedrock, Vertex AI, and Microsoft Foundry on June 9, 2026 with first-party pricing at $10 per 1M input tokens and $50 per 1M output tokens. Anthropic temporarily disabled Fable 5 access on June 12, 2026 after a US export control directive and redeployed Fable 5 and Mythos 5 on July 1, 2026.

Model Specs

Released2026-06-09
Context1m
ArchitectureDecoder Only

Provider

Vercel AI Gateway
Vercel AI Gateway

Vercel