---
title: "Claude Code"
description: "Use Claude Code with Bifrost to route through any provider and unlock advanced features like MCP tools and observability."
icon: "star-of-life"
---

[Claude Code](https://www.claude.com/product/claude-code) brings AI-powered coding capabilities directly to your terminal.

<Note>
  If your Allowed Headers are already set to `*`, you can skip this note. If not and you face issues integrating Bifrost
  with Claude Code, try switching to `*` or adding the specific headers required by your client. By default, Bifrost
  whitelists: `Content-Type`, `Authorization`, `X-Requested-With`, `X-Stainless-Timeout`, and `X-Api-Key`.
</Note>

## To install Claude code

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

## Configuring Claude Code to work with Bifrost

Claude Code supports multiple authentication methods. Choose the one that matches your account type.

1. **Set environment variables**

   ```bash
   export ANTHROPIC_API_KEY=your-bifrost-virtual-key  # or "dummy" if virtual keys are not enabled
   export ANTHROPIC_BASE_URL=http://localhost:8080/anthropic
   ```

2. **Run Claude Code**

```bash
claude
```

## Setup with the VS Code extension

If you prefer using Claude Code inside VS Code, install the [Claude Code extension](https://marketplace.visualstudio.com/items?itemName=anthropic.claude-code) and point it to Bifrost using the same environment variables you use for the CLI.

### 1. Install the extension

1. Open **Extensions** in VS Code (`Cmd+Shift+X` on macOS)
2. Search for **Claude Code**
3. Install **Claude Code** by Anthropic

### 2. Configure Bifrost endpoint

Add Bifrost variables in your editor settings:

```json
{
  "claudeCode.disableLoginPrompt": true,
  "claudeCode.environmentVariables": [
    {
      "name": "ANTHROPIC_BASE_URL",
      "value": "http://localhost:8080/anthropic"
    },
    {
      "name": "ANTHROPIC_DEFAULT_SONNET_MODEL",
      "value": "vertex/claude-sonnet-4-6"
    },
    {
      "name": "ANTHROPIC_DEFAULT_HAIKU_MODEL",
      "value": "vertex/claude-haiku-4-5"
    }
  ]
}
```

If virtual keys are enabled, also add `ANTHROPIC_API_KEY` in the same list (use your Bifrost virtual key value). If not, set it to `dummy`.

## Amazon Bedrock via Bifrost

### Setup

Configure environment variables

```bash
   export ANTHROPIC_API_KEY=bifrost-virtual-key
   export ANTHROPIC_BASE_URL=http://localhost:8080/anthropic
```

### Pin model versions (recommended)

```bash
export ANTHROPIC_DEFAULT_SONNET_MODEL="bedrock/global.anthropic.claude-sonnet-4-6"
export ANTHROPIC_DEFAULT_HAIKU_MODEL="bedrock/global.anthropic.claude-haiku-4-5-20251001-v1:0"
```

If you don't pin using CLI - you can pin these in UI. Go to Dashboard > Models > Model Providers > AWS Bedrock > Key. And add deployments

<Frame>
  <img src="/media/cli/claude-bedrock-pinning.png" alt="Claude bedrock pinning" />
</Frame>

### Start Claude Code

```
claude
```

<Warning>
  Always pin model versions with `ANTHROPIC_DEFAULT_*_MODEL` when using Bedrock. Without pinning, Claude Code aliases
  resolve to the latest version, which may not be enabled in your Bedrock account.
</Warning>

## Google Vertex AI via Bifrost

### Setup

Configure environment variables

```bash
   export ANTHROPIC_API_KEY=bifrost-virtual-key
   export ANTHROPIC_BASE_URL=http://localhost:8080/anthropic
```

### Pin model versions (recommended)

```bash
export ANTHROPIC_DEFAULT_SONNET_MODEL="vertex/claude-sonnet-4-6"
export ANTHROPIC_DEFAULT_HAIKU_MODEL="vertex/claude-haiku-4-5"
```

### Start Claude Code

```
claude
```

## Azure via Bifrost

### Setup

Configure environment variables

```bash
   export ANTHROPIC_API_KEY=bifrost-virtual-key
   export ANTHROPIC_BASE_URL=http://localhost:8080/anthropic
```

### Pin model versions (recommended)

```bash
export ANTHROPIC_DEFAULT_SONNET_MODEL="azure/claude-sonnet-4-6"
export ANTHROPIC_DEFAULT_HAIKU_MODEL="azure/claude-haiku-4-5"
```

You will also have to map these model names to actual deployment names on Bifrost dashboard.

<Frame>
  <img src="/media/cli/claude-azure-pinning.png" alt="Claude bedrock pinning" />
</Frame>

### Start Claude Code

```
claude
```

<Warning>
  Azure-hosted models must support **tool use capabilities** for Claude Code to function properly. Verify tool calling
  support before configuring Azure models.
</Warning>

## Model Configuration

Claude Code uses three model tiers: **Sonnet** (default), **Opus** (complex tasks), and **Haiku** (fast, lightweight). With Bifrost, you can override these defaults to use any model from any provider.

**Override Default Models:**

Set environment variables to replace Claude Code's default model tiers with any Bifrost-configured model:

```bash
# Replace Sonnet tier with GPT-5
export ANTHROPIC_DEFAULT_SONNET_MODEL="openai/gpt-5"

# Replace Opus tier with Claude Opus 4.5
export ANTHROPIC_DEFAULT_OPUS_MODEL="anthropic/claude-opus-4-5-20251101"

# Replace Haiku tier with Azure-hosted Claude
export ANTHROPIC_DEFAULT_HAIKU_MODEL="azure/claude-haiku-4-5"
```

<Warning>
  Alternative models must support **tool use capabilities** for file operations, terminal commands, and code editing to
  work properly with Claude Code.
</Warning>

**Start with a Specific Model:**

Launch Claude Code with a specific model using the `--model` flag:

```bash
# Start with Opus
claude --model claude-opus-4-5-20251101

# Start with Haiku for lightweight tasks
claude --model claude-haiku-4-5-20251001
```

## Switching Models Mid-Session

Use the `/model` command to switch models during an active session:

```bash
# Using full model names
/model claude-opus-4-5-20251101 # This will be used from anthropic provider
/model claude-sonnet-4-5-20250929 # This will be used from anthropic provider

# Using different providers dynamically via Bifrost
/model vertex/claude-haiku-4-5
/model azure/claude-sonnet-4-5
/model bedrock/claude-sonnet-4-5
```

<Tip>
  Run `/model` without arguments to check your current model. The switch is instantaneous and Claude Code seamlessly
  continues your conversation context with the new model.
</Tip>

<Warning>
  If you use Claude-specific features like **web search**, **computer use**, or **citations**, ensure the model you
  switch to also supports these capabilities. Non-Claude models or Claude models on certain providers may not support
  all features.
</Warning>

## Provider Compatibility

<Warning>
**Not all providers work well with Claude Code**. Since Claude Code heavily relies on tool calling for file operations, terminal commands, and code editing, providers must properly support and stream tool call arguments.

**Known Issues:**

- **OpenRouter**: Does not stream function call arguments properly. Tool calls return with empty `arguments` fields, causing Claude Code to fail when attempting file operations or other tool-based actions.
- **Some proxy providers**: May not fully implement the Anthropic API streaming specification for tool calls.

If you experience issues with tool calls not executing properly, try switching to a different provider in your Bifrost configuration.

</Warning>