[BUG] Claude for Excel/PowerPoint: 'Enterprise gateway' login option not visible in add-in

Resolved 💬 2 comments Opened Mar 11, 2026 by pramirez140 Closed Mar 11, 2026

What's Wrong?

The Claude for Excel/PowerPoint add-in documentation states that users should see an "Enterprise gateway" option on the sign-in screen to connect via custom LLM gateways. However, this option is not visible in the add-in interface.

According to the official documentation:

"On the sign-in screen, select 'Enterprise gateway.' Enter the Gateway URL and API token your IT team provided."

The option simply does not appear, making it impossible to use Azure AI Foundry credits or custom LLM gateways (like LiteLLM) with the Excel/PowerPoint add-ins.

What Should Happen?

On the sign-in screen of the Claude for Excel/PowerPoint add-in, there should be a visible "Enterprise gateway" option that allows users to:

Enter a custom Gateway URL
Enter an API token
Connect to custom LLM gateways or Azure AI Foundry endpoints

Error Messages/Logs

No error messages - the option is simply not present in the UI. The sign-in screen only shows standard authentication options without the enterprise gateway alternative.

Steps to Reproduce

Install Claude for Excel add-in from Microsoft AppSource
Open Excel and launch the Claude add-in
Look at the sign-in screen for "Enterprise gateway" option
Option is not visible - only standard login options appear

Context

I'm trying to use Claude for Excel with Azure AI Foundry (Microsoft Foundry) credentials via a LiteLLM proxy. The setup works correctly when tested via curl:

# LiteLLM proxy running locally with Cloudflare tunnel
curl -s https://my-tunnel.trycloudflare.com/v1/models \
  -H "Authorization: Bearer sk-my-token"
# Returns: {"data": [{"id": "claude-sonnet-4-5", ...}]}

# API calls work correctly
curl -s https://my-tunnel.trycloudflare.com/v1/chat/completions \
  -H "Authorization: Bearer sk-my-token" \
  -H "Content-Type: application/json" \
  -d '{"model": "claude-sonnet-4-5", "messages": [{"role": "user", "content": "Hello"}]}'
# Returns valid Claude response

The LiteLLM proxy correctly exposes /v1/models and /v1/messages endpoints as required by the documentation, but there's no way to enter this configuration in the add-in.

Claude Model

N/A - Cannot reach model selection due to authentication limitation

Is this a regression?

Unknown - First time attempting to use enterprise gateway feature

Claude Code Version

claude --version: 1.0.202 (Claude Code)

Platform

API Platform: Azure AI Foundry (Microsoft Foundry) via LiteLLM proxy
Operating System: macOS Tahoe 26.2
Terminal/Shell: zsh
Excel Version: Microsoft Excel for Mac (Microsoft 365)

Additional Information

Workaround Attempted

Set up LiteLLM as a proxy to Azure AI Foundry with Cloudflare tunnel for public URL access:

# litellm_config.yaml
model_list:
  - model_name: claude-sonnet-4-5
    litellm_params:
      model: azure_ai/claude-sonnet-4-5
      api_base: https://my-resource.services.ai.azure.com/anthropic
      api_key: "my-azure-api-key"

general_settings:
  master_key: "sk-litellm-azure-proxy"

This setup works for:

✅ Claude Code CLI (via ANTHROPIC_BASE_URL)
✅ Cursor and other OpenAI-compatible apps
❌ Claude for Excel/PowerPoint (no way to enter gateway URL)

Questions

Is the "Enterprise gateway" option only available for certain subscription tiers?
Is there a minimum add-in version required?
Are there regional restrictions for this feature?