> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hopscotchlabs.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Claude Code

> What Claude Code needs from an endpoint, why this API's published surface is not it yet, and the settings to know when that changes.

export const FeatureStatus = ({missing, feature, instead, detail, children}) => <Info>
    <strong>Not available yet: {missing ?? feature}.</strong>
    {instead ?? detail ? ` ${instead ?? detail}` : null} This page documents what
    the product does today. When that changes, this page changes with it.
    {children}
  </Info>;

[Claude Code](https://code.claude.com/docs) is Anthropic's terminal coding
agent. It can be pointed at a custom endpoint, and people do point it at
gateways, so it is a reasonable thing to try here. It will not work here yet,
and this page says exactly why and exactly what it would take.

<FeatureStatus missing="an Anthropic Messages endpoint on this API's published surface" instead="Claude Code speaks the Anthropic Messages API and nothing else. This site publishes the OpenAI chat completions and Responses surfaces, and it publishes nothing about a Messages endpoint. Until it does, there is no base URL you can give Claude Code that this site can tell you the behaviour of." />

## The one thing that decides it

Claude Code does not speak OpenAI chat completions. Anthropic's own gateway
documentation lists exactly three client formats it will use, and the one
selected by a custom base URL is the Anthropic Messages API, posted to
`/v1/messages` on whatever origin you give it. There is no OpenAI-compatible
mode, and Anthropic states that it does not support routing Claude Code to
non-Claude models through a gateway.

So this is not a configuration problem. Pointing Claude Code at the base URL
that works for every other harness on this site sends it to an endpoint this
site does not publish, and nothing on these pages tells you what comes back.

**What would change it:** a Messages endpoint on the published surface, in the
tracker, shipped. When that lands this page stops being a warning and becomes a
configuration page, and the settings below are the ones it will use.

## What Claude Code would need, and where this API already agrees

Worth writing down, because two of these are already true here and are the parts
people usually get wrong.

**The base URL is an origin, with no `/v1`.** Claude Code appends `/v1/messages`
itself, along with a query string. Every other harness on this site wants the
`/v1` included, so this one is the exception rather than the rule, and pasting
the value from another page would be wrong twice over.

**The credential goes in `ANTHROPIC_AUTH_TOKEN`, not `ANTHROPIC_API_KEY`.**
The two are not aliases: `ANTHROPIC_AUTH_TOKEN` sends `Authorization: Bearer`,
and `ANTHROPIC_API_KEY` sends `x-api-key`. This API reads `Authorization:
Bearer` and nothing else, so `ANTHROPIC_AUTH_TOKEN` is the one that would be
read here, and it is also the one Anthropic recommends for a third-party
gateway. [Authentication](/get-started/authentication) covers the header.

**Model ids would not be a problem.** Anthropic states that Claude Code's model
id check runs only against Anthropic's own API, and that behind a custom base
URL the gateway defines the names, so any string is passed through. A slashed,
provider-prefixed id is explicitly supported, which is the shape this API needs.
There are several ids to pin rather than one: a session model, and separate
family settings of which the small fast one drives background work.

**Token counting would not be a problem either.** Claude Code will use a
token-counting endpoint when one exists and count through the inference
endpoint when one does not. Its absence costs requests, not correctness.

**Streaming would be mandatory, with keep-alive frames.** Claude Code reads the
stream as it arrives and gives up on one that goes quiet, counting keep-alive
frames as traffic. A response assembled and sent in one piece stalls it.

## What we did not verify

* Anything about a Messages endpoint on this platform. This site publishes
  none, so this page makes no claim about one, including no claim about what a
  request to that path does today.
* That any Claude Code session against this API succeeds or fails in any
  particular way. Nothing was run.
* Whether Claude Code's adaptive thinking field would be accepted. Claude Code
  sends it without a matching beta header for model names it does not
  recognise, which includes any id a gateway defines, and an endpoint that
  rejects it answers `400` naming the field. Claude Code has a setting that
  turns it off. We have not tested the interaction.
* Which of the model settings a working configuration would actually need to
  pin. Anthropic's documentation does not state a number and we are not going
  to invent one.