Claude Code

Claude Code is Anthropic's AI coding tool. It runs in the terminal and in VS Code. Claude Code connects to Echo in the Anthropic format.

Tested: Claude Code 2.1.278 (2026-09-27, Echo's test environment)

Before you start

• Claude Code uses Claude models. Anthropic does not support using models other than Claude through a relay service (gateway) such as Echo. Anthropic also does not recommend, maintain or audit gateway products
• While an Echo key is set, your claude.ai subscription is not used. Charges are deducted from your Echo balance
• Have your Echo API key and the ID of the Claude model you want to use ready. The Claude models we offer and their IDs are in the model list

Set up

Set it up in the terminal

Set the following environment variables (named values set on your computer). Replace sk-... with your Echo API key and the model IDs with the IDs of the models you want to use.

export ANTHROPIC_BASE_URL="https://token.echohub.io"
export ANTHROPIC_AUTH_TOKEN="sk-..."
export ANTHROPIC_MODEL="claude-sonnet-5"
export ANTHROPIC_DEFAULT_OPUS_MODEL="claude-opus-5-5"
export ANTHROPIC_DEFAULT_SONNET_MODEL="claude-sonnet-5"
export ANTHROPIC_DEFAULT_HAIKU_MODEL="claude-haiku-4-5"

• If you do not set a model ID, Claude Code calls its own default model ID. If Echo does not offer that ID, you get an error, and it takes more than a minute to appear (see "Known issues" below)
• Set the three variables such as ANTHROPIC_DEFAULT_OPUS_MODEL to IDs of models that Echo offers as well. If you set an ID that Echo does not offer, you get an error whenever that model is used
• If ANTHROPIC_API_KEY holds another key (such as an Anthropic key), delete it before setting these. Claude Code sends the key in this variable in the x-api-key header

Put it in the settings file

To avoid setting them every time, put them in env in ~/.claude/settings.json (%USERPROFILE%\.claude\settings.json on Windows).

{
  "env": {
    "ANTHROPIC_BASE_URL": "https://token.echohub.io",
    "ANTHROPIC_AUTH_TOKEN": "sk-...",
    "ANTHROPIC_MODEL": "claude-sonnet-5",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "claude-opus-5-5",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "claude-sonnet-5",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "claude-haiku-4-5"
  }
}

If the same variable is set both in the shell and in the settings file, the value in the settings file is used.

Note: Do not put your key in the project's .claude/settings.json. That file goes into the repository and is shared with others.

Use the VS Code extension

Put them in claudeCode.environmentVariables in your VS Code user settings (open them with the command "Preferences: Open User Settings (JSON)"). The extension checks the credentials in this setting before it starts.

{
  "claudeCode.environmentVariables": [
    { "name": "ANTHROPIC_BASE_URL", "value": "https://token.echohub.io" },
    { "name": "ANTHROPIC_AUTH_TOKEN", "value": "sk-..." },
    { "name": "ANTHROPIC_MODEL", "value": "claude-sonnet-5" }
  ]
}

Check that it works

1. In the terminal where you set the environment variables, run the following command. If the last line shows 200 and above it is JSON containing "type":"message", the base URL and the key are set correctly

curl -sS -w '\n%{http_code}\n' -X POST "$ANTHROPIC_BASE_URL/v1/messages" \
  -H "Authorization: Bearer $ANTHROPIC_AUTH_TOKEN" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{"model": "claude-sonnet-5", "max_tokens": 16, "messages": [{"role": "user", "content": "こんにちは"}]}'

2. In the same terminal, start claude and run /status. Check that the base URL is https://token.echohub.io and that ANTHROPIC_AUTH_TOKEN is shown as the credential
3. Ask something. If an answer comes back without errors, you are done. The call also appears in 「呼び出し履歴」 (Call history) in the console

Known issues

The following behavior was checked in Echo's test environment on 2026-09-27.

Cases where the upstream API returns an error, and the list of error bodies, are in Errors and fixes.

Troubleshooting

Claude Code attaches IDs that identify the device and the session to its requests. Echo passes this value unchanged to the upstream Anthropic API. Details are in Data handling.

Sources