Claude Code brings AI-powered coding capabilities directly to your terminal.
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.
To install Claude code
npm install -g @anthropic-ai/claude-code
Configuring Claude Code to work with Bifrost
To avoid getting into different caching issues of Claude code -
- Ensure there is no
model field in settings.json. If it’s present remove it. This overwrites the env model selection.
- Once you update the
settings.json, start claude, and execute /logout. And restart - select use API key even if its not recommended.
- Update settings.json
Global settings.json is placed in your home folder.
- macOS / Linux / WSL (User Global):
~/.claude/settings.json
- Windows (User Global):
%USERPROFILE%\.claude\settings.json
- Project-Specific:
.claude/settings.json (located within your individual project’s root directory)
- Local Overrides:
.claude/settings.local.json (also in the project root, used for personal preferences that aren’t shared via Git)
You will need to update the most granular settings.json.
1. Using alias
- Add following routing rules in Bifrost
sonnet-model route
- Keep it a global level and assign priority you want to assign
- Add model condition as
model = sonnet-model. This option is not available out of the box - so type this string and select Create sonnet-model
- And add second header condition; to check if the
user-agent starts with claude-cli.
- And then you can map this model to any model you want. In the configuration given - we are using
vertex/claude-sonnet-4-6.
haiku-model route
- Repeat the above steps by replacing
sonnet-model with haiku-model.
- Update
settings.json
The JSON snippets below show only the env key. Merge them into your existing settings.json top-level
object — do not paste them as a standalone file, or you will overwrite other settings like permissions,
model, and apiKeyHelper.
"env": {
"ANTHROPIC_BASE_URL": "http://localhost:8080/anthropic",
"ANTHROPIC_API_KEY": "your-virtual-key",
"ANTHROPIC_DEFAULT_HAIKU_MODEL": "haiku-model",
"ANTHROPIC_DEFAULT_SONNET_MODEL": "sonnet-model"
}
2. Using provider-specific model pinning
Anthropic
Update settings.json to pick Anthropic models. For Anthropic models, you don’t need to prefix models with provider name.
"env": {
"ANTHROPIC_BASE_URL": "http://localhost:8080/anthropic",
"ANTHROPIC_API_KEY": "your-virtual-key",
"ANTHROPIC_DEFAULT_HAIKU_MODEL": "claude-haiku-4-6",
"ANTHROPIC_DEFAULT_SONNET_MODEL": "claude-sonnet-4-6"
}
Bedrock
Update settings.json to pick Anthropic models on Bedrock.
"env": {
"ANTHROPIC_BASE_URL": "http://localhost:8080/anthropic",
"ANTHROPIC_API_KEY": "your-virtual-key",
"ANTHROPIC_DEFAULT_HAIKU_MODEL": "bedrock/global.anthropic.claude-haiku-4-6",
"ANTHROPIC_DEFAULT_SONNET_MODEL": "bedrock/global.anthropic.claude-sonnet-4-6"
}
Vertex
Update settings.json to pick Anthropic models on Vertex.
"env": {
"ANTHROPIC_BASE_URL": "http://localhost:8080/anthropic",
"ANTHROPIC_API_KEY": "your-virtual-key",
"ANTHROPIC_DEFAULT_HAIKU_MODEL": "vertex/claude-haiku-4-6",
"ANTHROPIC_DEFAULT_SONNET_MODEL": "vertex/claude-sonnet-4-6"
}
Azure
Update settings.json to pick Anthropic models on Azure.
"env": {
"ANTHROPIC_BASE_URL": "http://localhost:8080/anthropic",
"ANTHROPIC_API_KEY": "your-virtual-key",
"ANTHROPIC_DEFAULT_HAIKU_MODEL": "azure/claude-haiku-4-6",
"ANTHROPIC_DEFAULT_SONNET_MODEL": "azure/claude-sonnet-4-6"
}
Azure-hosted models must support tool use capabilities for Claude Code to function properly. Verify tool calling
support before configuring Azure models.
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.
Start with a Specific Model:
Launch Claude Code with a specific model using the --model flag:
# 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:
# 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
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.
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.
Provider Compatibility
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. Checklist
- Ensure the model selected is same as you configured in the
settings.json.
If this is not the case -
- Select model using /config
- Execute
/config
- Search for model
- Select the correct model
- Or pass the model using
/model <model_name> e.g., /model sonnet-model
