[DOCS] Clarify: Claude for Excel/PowerPoint 'Enterprise gateway' not available - LiteLLM works for Claude Code only

Summary

This is a documentation/clarification request after testing LiteLLM gateway with multiple Claude products.

What Works ✅

Claude Code CLI works perfectly with LiteLLM proxy + Azure AI Foundry:

export ANTHROPIC_BASE_URL="https://my-tunnel.trycloudflare.com"
export ANTHROPIC_AUTH_TOKEN="sk-litellm-azure-proxy"
claude
# Works! Can use Azure credits through LiteLLM proxy

Other OpenAI-compatible apps (Cursor, Continue, etc.) also work via LiteLLM.

What Doesn't Work ❌

Claude for Excel and Claude for PowerPoint add-ins do NOT show the "Enterprise gateway" login option documented here:
https://support.claude.com/en/articles/13945233-use-claude-for-excel-and-powerpoint-with-an-llm-gateway

The documentation states:

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

But this option simply does not appear in the add-in UI.

The Confusion

The documentation at https://code.claude.com/docs/en/llm-gateway covers LLM gateway configuration, but it's unclear that:

1. This only applies to Claude Code CLI, not to Office add-ins
2. Claude for Excel/PowerPoint may require different configuration or subscription tier
3. There's no public repo to report Office add-in issues

Request

Please clarify in the documentation:

1. Which products support LLM gateways?

• Claude Code CLI ✅
• Claude for Excel ❓
• Claude for PowerPoint ❓
• Claude Cowork ❓

1. If Excel/PowerPoint support enterprise gateways:

• What subscription tier is required?
• How to access the option?
• Is it region-restricted?

1. Where to report Office add-in bugs (since this repo is marked invalid for such issues)

Environment

• LiteLLM proxy with Azure AI Foundry backend
• Cloudflare tunnel for public HTTPS URL
• All endpoints working (/v1/models, /v1/messages, /v1/chat/completions)
• macOS + Microsoft Excel for Mac (Microsoft 365)

Related

• Issue #33388 (marked invalid - was about the same problem)
• Documentation: https://support.claude.com/en/articles/13945233-use-claude-for-excel-and-powerpoint-with-an-llm-gateway