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

# Arcus MCP server

> Connect your AI assistant to the Arcus docs over the Model Context Protocol

Arcus exposes its documentation as a remote [Model Context Protocol](https://modelcontextprotocol.io) (MCP) server. Once connected, your AI assistant can search the REST and WebSocket reference, surface examples, and answer questions like *"where do I set TP/SL?"* without leaving your editor.

## Server details

| Field          | Value                                      |
| -------------- | ------------------------------------------ |
| URL            | `https://docs.arcus.xyz/mcp`               |
| Transport      | HTTP (streamable)                          |
| Authentication | OAuth 2.0 with dynamic client registration |
| Discovery      | `/.well-known/oauth-protected-resource`    |

<Note>
  Browsing the MCP URL directly in a browser returns `401 invalid_token` — that is the standard MCP-spec advertisement of the OAuth flow ([RFC 9728](https://www.rfc-editor.org/rfc/rfc9728)). MCP clients follow the `WWW-Authenticate` header to complete authentication automatically; you do not need a personal access token.
</Note>

## What you can ask

After connecting, your assistant can answer questions grounded in the live spec:

<CardGroup cols={2}>
  <Card title="API behavior" icon="circle-question">
    *"Which endpoint takes TP/SL — `placeOrder` or `batchPlaceOrder`?"*
  </Card>

  <Card title="Auth flow" icon="key">
    *"Show me how to sign a request with my Ed25519 API key."*
  </Card>

  <Card title="WebSocket channels" icon="bolt">
    *"What channels stream order book updates and what do their payloads look like?"*
  </Card>

  <Card title="Code samples" icon="code">
    *"Give me a TypeScript snippet that cancels all open orders for one market."*
  </Card>
</CardGroup>

## Connect your editor

<CardGroup cols={3}>
  <Card title="Claude Code" icon="asterisk" href="/ai-tools/claude-code">
    Remote MCP via `claude mcp add`.
  </Card>

  <Card title="Cursor" icon="arrow-pointer" href="/ai-tools/cursor">
    Add through Cursor MCP settings.
  </Card>

  <Card title="Windsurf" icon="water" href="/ai-tools/windsurf">
    Configure in Cascade's MCP panel.
  </Card>
</CardGroup>

## Troubleshooting

<AccordionGroup>
  <Accordion icon="lock" title="The browser shows 401 / invalid_token">
    Expected. The endpoint is an OAuth-protected MCP resource; browsers do not run the MCP OAuth flow. Use a real MCP client (Claude Code, Cursor, Windsurf, Claude Desktop) — it will redirect you through a one-time authentication and then connect.
  </Accordion>

  <Accordion icon="arrow-rotate-right" title="Authentication popup never opens">
    Update your client to the latest version — MCP HTTP-transport OAuth support is recent. For Claude Code: `npm i -g @anthropic-ai/claude-code`. Then remove and re-add the server.
  </Accordion>

  <Accordion icon="circle-question" title="The assistant gives stale answers">
    The MCP server reflects the current published spec. If something looks wrong, open an issue and link to the page — we resync from upstream on every merge.
  </Accordion>
</AccordionGroup>