# Claude Sonnet 5.5 is now available on Tchavi

> Claude Sonnet 5.5 is open on Tchavi: 1M-token context, 128K output, images and PDFs. What it does well, and its limit on forced tool calls.

- Published: 2026-10-05
- Author: Gael — Tchavi founder
- Canonical: https://tchavi.com/en/blog/claude-sonnet-5-5-now-on-tchavi

---


Claude Sonnet 5.5 is available on Tchavi today, under the ID `claude-sonnet-5-5`. If you already use Claude Sonnet 5, you can test it by changing one line. One thing to check first: if your code forces a specific tool call, read the section on tools below.

## In short

- Tchavi, an OpenAI-compatible AI API gateway you pay for with mobile money, adds Claude Sonnet 5.5: `claude-sonnet-5-5`.
- 1M-token context, output up to 128K tokens, image and PDF input, tool calling, streaming.
- Forced tool calls (`tool_choice` set to `any` or `tool`) are rejected by Anthropic on this model. `auto` works.
- Prices are on [the model page](https://tchavi.com/en/m/anthropic/claude-sonnet-5-5).

## What is new

Claude Sonnet 5.5 is the most recent model in Anthropic's Sonnet family. On Tchavi it has its own line in the catalogue: it does not replace Claude Sonnet 5, which stays available under its own ID. You choose when to move from one to the other.

## What it is for

Sonnet 5.5 is a general-purpose model built for long work:

- **Large documents.** A 200-page contract, a codebase or a quarter of support tickets fit in a single request thanks to the 1M-token window.
- **Long outputs.** Up to 128K tokens in one pass: a full report or a migration diff.
- **Vision and documents.** It reads images and PDFs in the same request as your text.
- **Adaptive thinking.** It decides how long to think and stays fast on easy turns.

These capabilities come from Anthropic's documentation, copied into our verified model sheet.

## What to know before you integrate it

Three behaviours matter if you are migrating existing code. I checked the first one directly against the API on the day the model was added.

**Forced tool calls are rejected.** Anthropic removed `tool_choice: any` and `tool_choice: tool` on this model: a request that forces a specific tool returns a 400 error. Tchavi does not emulate forced calls, so the request fails. If your integration depends on it, stay on Claude Sonnet 5.

**Sampling parameters are ignored.** Anthropic removed `temperature`, `top_p` and `top_k` on this model. Tchavi drops them from the request rather than letting it fail.

Third point, noted in the model sheet: text written between two tool calls arrives in thinking blocks, not as plain content. If your interface only shows streamed text, it can look idle while an agent is working.

## One call to try it

Same format as the OpenAI API, with Tchavi's base URL:

```bash
curl https://tchavi.com/api/v1/chat/completions \
  -H "Authorization: Bearer $TCHAVI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-5-5",
    "messages": [
      {"role": "user", "content": "Summarise this contract in five points, and list the clauses that allow a price increase."}
    ],
    "max_tokens": 1024
  }'
```

The cost of each call is in the `X-Credits-Used` response header. For Claude Code and Anthropic-format clients, the base URL is `https://tchavi.com/api`.

## How to try it

1. Open [the model page](https://tchavi.com/en/m/anthropic/claude-sonnet-5-5): prices, capabilities and limits, as billed.
2. Create an API key, then follow the [quickstart](https://tchavi.com/en/docs/quickstart) or the [chat completions](https://tchavi.com/en/docs/chat-completions) page.
3. Top up with mobile money from KES 250 (M-Pesa in Kenya, MTN or Airtel elsewhere; see [countries and operators](https://tchavi.com/en/docs/payments)). Credits you buy do not expire.

## FAQ

### Should I migrate from Claude Sonnet 5?

Not necessarily. Both stay available. Test Sonnet 5.5 on your own prompts and keep Sonnet 5 if you force tool calls.

### Are the prices on this page?

No. Prices change, and the model page always shows the price billed today.

### Can I use it with the OpenAI SDK?

Yes. Set the base URL to `https://tchavi.com/api/v1`, use your Tchavi key and pass `claude-sonnet-5-5` as the model.

[create your account and top up KES 250](https://tchavi.com/en/register?next=%2Fdashboard%2Fbilling%3Famount%3D250%26currency%3DKES%26from%3Dblog-sonnet-55-en)

> _This article is part of the series "Building an AI product from Africa". Tchavi is an OpenAI-compatible AI API gateway: one key gives access to over 100 text, image, audio and video models, and you pay for it with mobile money, no bank card ([countries and operators](https://tchavi.com/en/docs/payments)). More guides on [the blog](https://tchavi.com/en/blog). Follow us: [LinkedIn](https://www.linkedin.com/company/tchavi) and [X](https://x.com/tchaviai)._