# Claude Fable 5.2 is in AI Gateway, and it costs less than Fable 5.1

> Call Anthropic's newest Fable model on your ngrok credits or your own Anthropic key, at $8 input and $40 output per 1M tokens.

- Date: 2026-11-10
- Shipped by: Nijiko Yonskai and Jarod Clark
- Products: AI Gateway
- URL: https://ngrok.com/changelog/ai-gateway-claude-fable-5-2

Claude Fable 5.2, Anthropic's model for demanding reasoning and long agentic work, is now in AI Gateway as `anthropic/claude-fable-5-2`. Pay with your ngrok credits, or attach your own Anthropic key and let Anthropic bill you.

Every price is 20% lower than on Fable 5.1:

| Per 1M tokens          | Fable 5.2 | Fable 5.1 |
| ---------------------- | --------- | --------- |
| Input                  | $8.00     | $10.00    |
| Output                 | $40.00    | $50.00    |
| Cache read             | $0.20     | $0.25     |
| Cache write, 5 minutes | $10.00    | $12.50    |
| Cache write, 1 hour    | $16.00    | $20.00    |

![AI Gateway Models page in dark mode, filtered to fable, showing anthropic/claude-fable-5-2 at $8.00 per million input tokens and $40.00 per million output tokens above anthropic/claude-fable-5 and anthropic/claude-fable-5-1 at $10.00 and $50.00, all with 1M context windows and text, image, and file input.](https://ngrok.com/blog-assets/images/2026-11-10-ai-gateway-claude-fable-5-2/claude-fable-models-dark.png)

Fable 5.2 has a 1M-token context window and returns up to 128K tokens. It reads text, images, and PDFs. Images bill at the text input rate.

## Effort is your cost dial

Adaptive thinking is always on in Fable 5.2, and you can't turn it off. The model decides when to think, and `effort` sets how hard: `low`, `medium`, `high`, `xhigh`, or `max`. Anthropic's default is `high`, where the model thinks before almost every reply. Thinking tokens bill as output tokens, so effort also sets how much an answer costs.

In Anthropic's testing, a line such as "answer directly without deliberating" didn't stop the thinking at `medium` and above. For easy requests, lower the effort instead.

## Check your Fable 5.1 code before you switch

Anthropic returns a 400 error for four kinds of request that Fable 5.1 accepts, and AI Gateway passes the error back to you. They include forced tool use and `thinking` set to `enabled` or `disabled`. Leave `thinking` out and set effort instead. The [Fable 5.2 section of the Anthropic provider docs](https://ngrok.com/docs/ai-gateway/providers/anthropic#fable-5-2) lists all four.

AI Gateway doesn't offer fast mode for Fable 5.2. If you send `speed: "fast"`, the gateway removes it, and the request runs and bills at standard speed. The gateway also removes `temperature`, `top_p`, and `top_k`, which Fable 5.2 doesn't take. The `Ngrok-AIG-Removed-Params` response header names each field the gateway removed. See [Parameters the gateway removes](https://ngrok.com/docs/ai-gateway/providers/anthropic#parameters-the-gateway-removes).

If your apps send a [virtual model](https://ngrok.com/docs/ai-gateway/guides/virtual-models) name, move them to Fable 5.2 from the gateway: put `anthropic/claude-fable-5-2` at the top of its list, and the next request goes to Fable 5.2. Your code doesn't change. Before you switch, check that your apps don't send any of the four requests that Fable 5.2 rejects. After a 400, the gateway doesn't fall back to the next model in the list, so a request that worked on Fable 5.1 fails instead.

## Get started

[Create an ngrok account or sign in](https://app.ngrok.ai/). Create an [**access key**](https://app.ngrok.ai/keys) that allows Anthropic and Claude Fable 5.2. Confirm your account has credits, or [attach your own Anthropic key](https://ngrok.com/docs/ai-gateway/guides/attaching-provider-keys).

Fable 5.2 accepts requests in the Anthropic Messages format and in the OpenAI chat completions format. This example uses the Messages API, because that's where you set effort. On chat completions, the gateway removes `reasoning_effort` for every Claude model.

Optionally, try Fable 5.2 in the [playground](https://app.ngrok.ai/playground) first.

Follow the [**setup guide**](https://app.ngrok.ai/getting-started) and select **Anthropic** and **TypeScript**. The [Anthropic SDK guide](https://ngrok.com/docs/ai-gateway/sdks/anthropic) covers the rest of the SDK.

Install the Anthropic SDK and TypeScript runner:

```bash
npm install @anthropic-ai/sdk && npm install --save-dev tsx
```

Save your ngrok access key in `.env.local`. Keep this file out of version control:

```dotenv
AI_GATEWAY_API_KEY=your_access_key_here
```

Use an ES module project (`"type": "module"` in `package.json`) for top-level `await`. Save this example as `index.ts`:

```typescript
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
	baseURL: "https://gateway.ngrok.ai",
	apiKey: process.env.AI_GATEWAY_API_KEY,
});

const message = await client.messages.create({
	model: "anthropic/claude-fable-5-2",
	max_tokens: 16000,
	output_config: { effort: "medium" },
	messages: [{ role: "user", content: "Explain HTTP retries in two sentences." }],
});

for (const block of message.content) {
	if (block.type === "text") console.log(block.text);
}
console.log("Thinking tokens:", message.usage.output_tokens_details?.thinking_tokens);
```

Run the example from your project directory:

```bash
node --env-file=.env.local --import tsx index.ts
```

It prints a two-sentence answer, then the thinking token count. For a short question like this one, Fable 5.2 usually skips thinking at `medium`, so the count is 0. The answer's wording varies between runs.

The answer is in a `text` block. At higher effort, Fable 5.2 puts a `thinking` block in front of it, so loop over `message.content` instead of reading the first block.

Open [**Activity**](https://app.ngrok.ai/activity), find the request, and inspect its model, provider, status, token usage, and cost. To see what effort changes, set `effort` to `"high"`, Anthropic's default, and run the example again. In our runs, Fable 5.2 then thought for about 23 tokens before it answered. Compare the token usage and cost of the two requests.