# FAQ

> Frequent questions about access, billing, protocols and model selection.

## Access

### What exactly goes in base_url?

- OpenAI SDK / OpenAI-compatible clients: `https://api.tokrouter.dev/v1`
- Anthropic SDK: `https://api.tokrouter.dev` (the SDK appends `/v1/messages`)
- google-genai: `https://api.tokrouter.dev`

The two most common mistakes: dropping `/v1` for OpenAI clients, and adding `/v1` for Anthropic clients.

### Do I need a TokRouter SDK?

No. The gateway implements the vendors' native protocols, so you keep the official SDK and change the
base URL.

### How do I debug a 401?

1. Is the `Bearer ` prefix present (OpenAI protocol)?
2. Is the token deleted, expired or disabled?
3. Did you use your account password as the API key?

## Billing

### Are failed requests billed?

No. Only requests that actually return tokens count toward usage.

### Why is output so much more expensive than input?

Generating tokens costs upstream vendors far more than reading them. The gateway discloses each
component as the vendor prices it.

### What happens when the balance runs out?

A hard stop: every request returns an insufficient-quota error until you top up. A token-level quota cap
affects only that token.

## Protocols

### Can I call Claude with the OpenAI SDK?

Yes. Set `model` to a Claude id; the gateway maps it to the Anthropic protocol.

### Does Claude Code work?

Yes. Set `ANTHROPIC_BASE_URL` and `ANTHROPIC_AUTH_TOKEN` — see
[Claude Code](/en/integrations/claude-code/).

### Is streaming supported?

Yes, over SSE for all four inbound protocols. The one exception is `/v1/systemone`.

## Models

### Why does the docs' model list differ from /v1/models?

The docs page is a build-time snapshot; `/v1/models` is runtime truth. Use `/v1/models` for availability.

### Do dots and hyphens in model ids matter?

Yes. `claude-sonnet-5.5` and `claude-sonnet-5-5` are two different gateway ids (the first is the
gateway's naming, the second the vendor's canonical naming). When unsure, copy the id from
[Models](/en/models/).