# Claude API key (/docs/providers/anthropic-key)

The Claude API key account answers with a key from Anthropic. The wallet lists it as Claude under "With an API key", with the id `anthropic-key`. A Claude subscription is a separate account, described on the [Claude plan](/docs/providers/claude) page.

## What the visitor needs [#what-the-visitor-needs]

An Anthropic API key. Anthropic bills the account that owns the key.

## Connect [#connect]

1. The visitor creates an API key in Anthropic's console, on the account that should pay.
2. In the wallet, the visitor picks Claude under "With an API key".
3. The visitor pastes the key in the "Claude API key" field and presses Connect.

The wallet keeps the key in its encrypted vault, without the spaces around it. It makes no test call, and a wrong key shows up as the provider's error on the first answer. The key has no expiry in the wallet and stays in the vault until the visitor removes the account.

## Models [#models]

The wallet lists Anthropic's catalog from `https://api.anthropic.com/v1/models`, asked with the key, and keeps the list for a day. The visitor picks the account's default model in its settings, and a model per site with the buttons of the side panel. Without a choice, the account answers with `claude-haiku-5-5`.

## Usage and limits [#usage-and-limits]

The wallet reads `x-ratelimit-remaining-tokens` and `x-ratelimit-limit-tokens` on each answer that carries them. The room left is the remaining tokens divided by the limit. Without these headers, the card keeps saying "Usage shows after the first answer", and Auto ranks the account among the accounts with no reading.

## Calls [#calls]

Answers come from `https://api.anthropic.com/v1/messages` in Anthropic's Messages protocol, with the key in `x-api-key` and `anthropic-dangerous-direct-browser-access: true`. The wallet's header rule for `api.anthropic.com` applies to these calls as well: it removes `Origin` and sets Claude Code's `User-Agent`, `claude-cli/2.1.280 (external, Chrome)`.

The wallet leaves `temperature` and `topP` out of these calls, since current Claude models answer them with an error. That protocol requires an output limit on every call, and the wallet asks for 4096 tokens when your site sets no `maxTokens`. Claude Opus 5.5, Claude Sonnet 5.5 and Claude Fable 5.1 refuse a forced tool choice (`required` or a named tool), and their error reaches your site with its status.