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Claude for Office is Anthropic’s Microsoft 365 add-in that brings Claude directly into Word, Excel, PowerPoint, and Outlook. By routing Claude for Office through Bifrost, you get governance features like virtual keys, budget controls, rate limits, and built-in observability for all office-based AI usage across your organization. Claude for Office with Bifrost

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Setup

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1. Install the Add-in

Install the Claude for Office add-in from the Microsoft AppSource marketplace within any Office application (Word, Excel, PowerPoint, or Outlook). Organization admins can also deploy it centrally via the Microsoft 365 admin center.

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2. Log in and Select Enterprise Gateway

Open the Claude for Office add-in and log in to your account. On the login screen, select Enterprise Gateway as your connection method.

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3. Configure the API Endpoint

Enter your Bifrost endpoint as the Base URL: 
https://bifrost.example.com/anthropic
For local development: 
http://localhost:8080/anthropic

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4. Set Your API Key

Enter your Bifrost virtual key or Anthropic API key in the API Key field.

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5. Whitelist Required Headers

If your Allowed Headers are already set to *, you can skip this step.
Claude for Office requires the following headers to be in the Allowed Headers list. Go to Settings > Client Settings and add them as a comma-separated list: 
anthropic-dangerous-direct-browser-access, anthropic-version, content-type, user-agent, x-api-key, x-stainless-arch, x-stainless-helper-method, x-stainless-lang, x-stainless-os, x-stainless-package-version, x-stainless-retry-count, x-stainless-runtime, x-stainless-runtime-version, x-stainless-timeout

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6. Enable CORS

If your Allowed Origins are already set to *, you can skip this step.
Claude for Office makes requests from the pivot.claude.ai domain. Go to Settings > Client Settings and add the following origin to your Allowed Origins list: 
https://pivot.claude.ai
You’re all set — Claude for Office will now route all requests through Bifrost.

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How It Works

Claude for Office uses the Anthropic Messages API natively. Bifrost exposes a fully compatible Anthropic API at the /anthropic path, so the add-in works without any additional configuration beyond pointing it at your Bifrost instance. Bifrost automatically handles:
  • Model routing — requests are routed to the correct provider based on the model name
  • Tool stripping — server-side tools like code_execution, web_search, and web_fetch are automatically stripped to prevent API conflicts
  • Model metadata — token limits and capabilities are returned in list models responses for proper model selection in the add-in

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Using Other Providers (Azure, Vertex, Bedrock)

By default, Claude for Office sends requests to the Anthropic API. To route requests through Azure, Vertex AI, or Amazon Bedrock instead, you have two options:

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Option 1: Set the Model Name Directly

In the Claude for Office model selector, enter the provider-specific model name or deployment name. Bifrost will automatically route the request to the correct provider based on the model identifier. For example:
  • Azure: Enter your Azure deployment name (e.g., claude-opus-4-0)
  • Vertex AI: Enter the Vertex model ID (e.g., claude-opus-4@20250514)
  • Bedrock: Enter the Bedrock model ID (e.g., anthropic.claude-opus-4-0-20250514-v1:0)

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Option 2: Use Routing Rules

If you prefer to keep the default model names in Claude for Office and control routing server-side, create a routing rule in Bifrost. This lets you route requests to any provider — with fallbacks — without changing anything in the add-in. For example, you can create a rule that matches requests from Claude for Office (based on the origin header) and routes them to Azure with a Vertex AI fallback: Claude for Office routing rule This approach is ideal for organization-wide deployments where you want centralized control over which provider handles Claude for Office traffic.

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Using Virtual Keys

Bifrost Virtual Keys can be used as the API key in Claude for Office. This lets you:
  • Enforce per-user or per-team budgets and rate limits
  • Control which models and providers each user can access
  • Track usage and costs across your organization
  • Rotate credentials without updating every user’s add-in configuration
For organization-wide deployments, create separate virtual keys for each team or department to manage AI spend independently.

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Observability

All Claude for Office requests through Bifrost are logged. Monitor them at http://localhost:8080/logs — filter by provider, model, or search through conversation content to track usage patterns across your organization.

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Next Steps