Claude Code

Claude Code is Anthropic's terminal coding agent. It talks the Anthropic Messages API, which the gateway serves natively — so pointing it here takes two environment variables.

What you get

• Claude Code running against any Claude model the gateway exposes, billed to your project's sponsor budget.
• No Anthropic account or ANTHROPIC_API_KEY of your own.

Prerequisites

• Your project access key and base URL from your project control panel. This guide writes them as YOUR_PROJECT_KEY and https://v1.opentokenmarket.dev.

• Claude Code installed:

  npm install -g @anthropic-ai/claude-code
  

Configure

Set these in your shell (add them to ~/.zshrc / ~/.bashrc to make them stick):

export ANTHROPIC_BASE_URL="https://v1.opentokenmarket.dev"
export ANTHROPIC_AUTH_TOKEN="YOUR_PROJECT_KEY"

ANTHROPIC_AUTH_TOKEN (not ANTHROPIC_API_KEY) is what Claude Code sends as the bearer token to a custom endpoint.

To scope this to one project instead of your whole shell, put it in that project's .claude/settings.json:

{
  "env": {
    "ANTHROPIC_BASE_URL": "https://v1.opentokenmarket.dev",
    "ANTHROPIC_AUTH_TOKEN": "YOUR_PROJECT_KEY"
  }
}

Run

Pick a model from the model catalog and pass it with --model:

claude --model claude-sonnet-4-6

Set a default for the session instead of typing it each time:

export ANTHROPIC_MODEL="claude-sonnet-4-6"
claude

If the gateway maps a 1M-context variant, request it with the [1m] suffix:

claude --model 'claude-sonnet-4-6[1m]'

Verify

Before launching the agent, confirm the gateway answers:

curl https://v1.opentokenmarket.dev/v1/messages \
  -H "x-api-key: YOUR_PROJECT_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{"model":"claude-sonnet-4-6","max_tokens":64,"messages":[{"role":"user","content":"Say hi in 3 words."}]}'

A JSON response with a content array means you're connected.

Troubleshooting

• 401 / invalid x-api-key — you set ANTHROPIC_API_KEY instead of ANTHROPIC_AUTH_TOKEN, or the key is wrong. Re-copy it from your project control panel.
• 404 on /v1/messages — ANTHROPIC_BASE_URL has a trailing /v1. It should be the bare origin (https://v1.opentokenmarket.dev); Claude Code appends /v1/messages itself.
• budget has been exceeded — the project's funded balance is spent. Ask your sponsor to top up.
• Model not found — the name isn't on this gateway. Check the model catalog for the exact string.

Which model names to use

Use the Model name column from the model catalog verbatim — e.g. claude-sonnet-4-6, not anthropic/claude-....