Apply your own routing policies, reduce token costs automatically, and see every routing decision in real time with Merge Gateway.
How Claude Fable 5 performs*
Intelligence - general reasoning and knowledge
60
Coding - code generation and problem-solving
77
What Claude Fable 5 costs to run
| Vendor | Input / 1M tokens | Output / 1M tokens | Zero data retention |
| --- | ---: | ---: | --- |
| Anthropic | $10.00 | $50.00 | No |
Test Claude Fable 5
with Gateway’s Simulator
See a prompt's output, token spend, latency, and more with Claude Fable 5.
Route requests to Claude Fable 5 in minutes
To get started in seconds, add our Gateway Implementation skill to your project, or pick your preferred SDK below. Check out our other quick start skills here.
Install the Merge Gateway SDK
Python
1$ pip install merge-gateway-sdkSend a request
Python
1from merge_gateway import MergeGateway
2
3client = MergeGateway(api_key="YOUR_API_KEY")
4
5response = client.responses.create(
6 model="openai/gpt-5.2",
7 input=[
8 {"type": "message", "role": "system", "content": "You are a helpful programming tutor. Explain the concepts clearly with practical examples."},
9 {"type": "message", "role": "user", "content": "Explain the concept of recursion in programming with a simple set of examples."},
10 ],
11)
12
13print(response.output[0].content[0].text)Try a diffrent model
Swap the model string to route to a different provider. No other code changes needed.
Anthropic
1response = client.responses.create(
2 model="anthropic/claude-sonnet-4-20250514",
3 input=[
4 {"type": "message", "role": "system", "content": "You are a helpful programming tutor. Explain the concepts clearly with practical examples."},
5 {"type": "message", "role": "user", "content": "Explain the concept of recursion in programming with a simple set of examples."},
6 ],
7)Point to Gateway
Python
1from openai import OpenAI
2
3client = OpenAI(
4 api_key="YOUR_API_KEY",
5 base_url="https://api-gateway.merge.dev/v1/openai",
6)Send a request
Use the standard chat.completions.create method. No provider prefix needed on the model name.
Python
1response = client.chat.completions.create(
2 model="gpt-5.2",
3 messages=[
4 {"role": "system", "content": "You are a helpful programming tutor. Explain the concepts clearly with practical examples."},
5 {"role": "user", "content": "Explain the concept of recursion in programming with a simple set of examples."},
6 ],
7)
8
9print(response.choices[0].message.content)Install packages
1npm install merge-gateway-ai-sdk-provider aiCreate the provider
TypeScript
1import { createMergeGateway } from "merge-gateway-ai-sdk-provider";
2
3const gateway = createMergeGateway({
4 apiKey: "YOUR_API_KEY",
5});Send a request
Use generateText to send a request. Model names use the provider/model format.
TypeScript
1import { generateText } from "ai";
2
3const { text } = await generateText({
4 model: gateway("openai/gpt-4o"),
5 prompt: "Explain the concept of recursion in programming with a simple set of examples.",
6});
7
8console.log(text);If you already have @ai-sdk/openai installed, point it at Gateway with a base URL change:
TypeScript
1import { createOpenAI } from "@ai-sdk/openai";
2
3const gateway = createOpenAI({
4 apiKey: "YOUR_API_KEY",
5 baseURL: "https://api-gateway.merge.dev/v1/ai-sdk",
6});
7
8// All generateText/streamText calls work unchangedInstall the Merge Gateway SDK
Anthropic SDK
1from anthropic import Anthropic
2
3client = Anthropic(
4 api_key="YOUR_API_KEY",
5 base_url="https://api-gateway.merge.dev/v1/anthropic",
6)
7
8message = client.messages.create(
9 model="claude-sonnet-4-20250514",
10 max_tokens=1024,
11 messages=[
12 {"role": "user", "content": "Explain the concept of recursion in programming with a simple set of examples."},
13 ],
14)
15
16print(message.content[0].text)Explore other models available in Merge Gateway
Claude Fable 5 FAQ
In case you have any other questions on Claude Fable 5, we've answered a few more below. It's worth noting that the information below was written in July, 2026 and is subject to change.
Heading
What other models does Anthropic offer?
Anthropic ships a tiered Claude family so teams can match capability to task complexity and budget. Here are some other models Anthropic supports:
- Claude Opus 5: The current Opus-tier flagship, a same-price successor to Opus 4.8, built for complex agentic coding and enterprise work at roughly half of Fable 5's per-token cost
- Claude Sonnet 5: Anthropic's default mid-tier model, matching Fable 5's 1M-token context window at a fraction of the price, built for teams that want near-frontier coding and reasoning without frontier-tier spend
- Claude Opus 4.8: The prior-generation flagship that Opus 5 replaced, still available at its original rate and notable as the model Fable 5 automatically falls back to when a request trips its biology or chemistry safety classifier
How does Claude Fable 5 differ from Anthropic's other models?
Fable 5 sits at the top of Anthropic's price ladder, built on the same underlying model as the invitation-only Claude Mythos 5 but hardened with additional safety classifiers for general release.
- Pricing: Fable 5 costs $10 per million input tokens and $50 per million output tokens, exactly double Claude Opus 5's $5 and $25, and well above Claude Sonnet 5's standing rate of $3 and $15
- Benchmark scores: on the Artificial Analysis Intelligence Index, Fable 5 scores approximately 60, within a point of Opus 5's 61 and clearly ahead of Sonnet 5's 53, putting the two priciest Claude models effectively tied at the top of the index rather than Fable 5 holding a clean lead
- Reasoning mode: Fable 5 runs adaptive thinking always-on, the only current Claude model where this can't be switched off, while Opus 5 and Sonnet 5 offer it as a toggle and Haiku 4.5 relies on classic extended thinking instead
- Speed and latency: Anthropic rates Fable 5's comparative latency as "slower," and independent testing puts its time-to-first-token past a minute on complex prompts, well behind Opus 5's "moderate" rating and Sonnet 5's "fast" one
- Unique capabilities: Fable 5 leads the lineup on vision-heavy tasks, including reconstructing source code from screenshots and reading exact values off scientific figures, and on sustained autonomous agent runs, and it's the only model carrying Mythos-class safety classifiers for cybersecurity and biology or chemistry queries
Fable 5 is the right call for vision-heavy analysis, long-running autonomous agents, and cybersecurity- or biology-adjacent reasoning where the extra safety tooling and headroom matter. For general agentic coding or knowledge work, Opus 5 lands within a point of the same index score at half the price.
What models should I consider using alongside Claude Fable 5?
No single model is optimal for every task. Here are models worth pairing with Claude Fable 5 depending on what your product needs:
- GPT-5.4 Mini for high-volume classification, extraction, or routing tasks where Fable 5's reasoning depth and $50-per-million output price are unnecessary overhead
- Gemini 3.1 Pro Preview when the job is retrieval or synthesis across large multi-document or multimodal context rather than the multi-step reasoning Fable 5 specializes in
- Grok 4.5 for tasks that need current-events awareness or real-time data grounding, a gap Claude models don't specialize in
What are the challenges of using Claude Fable 5 in my product?
Like any production LLM, Claude Fable 5 comes with tradeoffs worth planning for:
- Provider dependency: routing every request straight to Anthropic's API means an outage, a rate-limit change, or a future deprecation of the claude-fable-5 model ID can take your product down with it unless a fallback path is already built
- Cost at scale: at $50 per million output tokens, the highest output price in Anthropic's current lineup, and with Fable 5's traces running notably verbose under always-on adaptive thinking, unmanaged usage compounds fast on agentic workflows that chain multiple calls
- Marginal gains over cheaper siblings: Fable 5's Intelligence Index score sits within a point of Opus 5's, and its reliable knowledge cutoff (January 2026) is actually older than Opus 5's (May 2026), so the 2x price premium doesn't automatically buy a proportional jump in capability or freshness for every workload
- Latency at default reasoning effort: time-to-first-token has been measured well past a minute on complex prompts, which rules Fable 5 out for synchronous, latency-sensitive UI paths without a faster fallback model in front of it
- Access can be gated or paused: Fable 5 rolled out in stages contingent on capacity and was briefly pulled back after launch to comply with export-control requirements, a reminder that the newest, most-restricted tier can see availability change with little warning
Why should I use Merge Gateway to route LLM requests with Claude Fable 5 and every other model?
Using Claude Fable 5 through Merge Gateway gives you access to the model itself and the infrastructure layer around it:
- One API, every provider: call Claude Fable 5 and every other major model through the same endpoint and API key, and move between providers by changing a model string instead of rewriting integration code
- Intelligent routing and automatic failover: Merge detects Anthropic outages and reroutes traffic automatically, and cost-, latency-, or quality-aware routing policies typically trim 40-60% off spend without any changes to your application
- Cost governance: cap Fable 5 spend with hard or soft project budgets, and see every request rolled up by model, project, and tag in one billing view that spans all your providers
- Build Your Own Router: decide what "best" means for your traffic by weighting curated ML benchmarks or your own eval scores, then let the router score every candidate model per request and explain, in plain language, why it picked the winner
- Security and compliance controls: screen requests with DLP rules and prompt injection defenses before they reach Anthropic, and lock in per-project model and region policies without building any of that logic yourself
How can I start routing requests to Claude Fable 5 via Merge Gateway?
Getting Claude Fable 5 running through Merge Gateway takes a few minutes:
1. Create an account and get your API key from the dashboard.
2. Install the Merge Gateway SDK: run pip install merge-gateway-sdk (Python) or npm install merge-gateway-sdk (Node). Alternatively, if you're already using the OpenAI SDK, set base_url = "https://api-gateway.merge.dev/v1/openai" and your existing code works as-is.
3. Make your first request using the provider/model format. For Claude Fable 5, the model string is anthropic/claude-fable-5. Swap the model string to route to any other provider without changing anything else.
4. Configure a routing policy in the dashboard to set failover behavior, cost limits, and optimization strategy. Your first policy can be as simple as naming Claude Fable 5 as primary with one fallback.
Full setup instructions and SDK references are in the Merge Gateway docs.
Try Claude Fable 5 through Merge Gateway
Route, observe, and control AI requests across providers from one API.
