Claude for Microsoft 365

Claude for Microsoft 365 is Anthropic's official addin for Word, Excel, PowerPoint, and Outlook. By pointing it at a running Tresor instance, you can keep the Anthropic client experience while hot-switching the underlying model between Anthropic, DeepSeek, MiniMax, a local llama.cpp server, or any other configured downstream — all from the web UI.

No need to worry about the different API format underlying model is using, Tresor will auto-translate between the Anthropic API (Claude Desktop) to other API formats (e.g., gpt-5.5 using OpenAI Responses).

This page shows how to wire Claude for Microsoft 365 to Tresor.

✅ Prerequisites

• Installed Tresor following installation guide.
• Claude for Microsoft 365 installed.

1. Configure Tresor

There are two ways to prepare Tresor:

Web UI

Web UI is more intuitive, but require more manual operations.

1. In "Downstreams" tab

   • Click + Add Provider to add the LLM provider you are about to use.

2. In "Aliases" tab

   • Click + New Alias Group

     • Input Model ID: claude-opus.*
     • Checked "Regex Pattern"
     • Select the Downstream and Output Model IDs you added previously.

   • Repeat the above add new alias group process to add claude-sonnet.* and claude-haiku.*

   • Click + Add Name:

     • For alias claude-opus.*: Add announced name claude-opus
     • For alias claude-sonnet.*: Add announced name claude-sonnet
     • For alias claude-haiku.*: Add announced name claude-haiku

     WARNING: Unlike Claude Code's setup guide, announced names are required to allow Claude for Microsoft 365 to detect available models!

3. In "Settings" tab

   • Click + Add API Key under "Proxy Authentication" section (e.g, sk-proxy-123). Copy it, and we are about to fill it into "Token" in the following section.

config.yaml

Editing yaml is less intuitive, but require less manual operations.

The following example config.yaml uses 3 downstream providers. Replace them based on your actual providers.

~/.config/tresor/config.yaml

bind_addr: 127.0.0.1:11510
proxy_api_keys:
- sk-proxy-123
... # Omitted showing other settings here
downstreams:
  - id: llama-cpp
    name: llama.cpp
    base_url: http://127.0.0.1:3000 # change to your actual llama.cpp listening port
    api_formats:
        - openai
        - anthropic
    output_model_ids:
        - qwen3.8:27b-coder
        - qwen3.8:27b:instruct
  - id: deepseek
    name: DeepSeek
    base_url: https://api.deepseek.com
    api_formats:
        - openai
        - openai_responses
        - anthropic
    output_model_ids:
        - deepseek-flash
        - deepseek-v4-pro
    is_enabled: true
    auth:
        type: api_key
        api_key: sk-YOUR-DEEPSEEK-API-KEY
    format_urls:
        anthropic: https://api.deepseek.com/anthropic
  - id: minimax
    name: MiniMax
    base_url: https://api.minimaxi.com/anthropic
    api_formats:
        - anthropic
    output_model_ids:
        - MiniMax-M2.5
        - MiniMax-M2.7
        - MiniMax-M3
aliases:
  - input_model_id: claude-opus.*
    is_regex: true
    announced_names:
        - claude-opus
        - claude-opus-5
    options:
        - id: alias-minimax-m3
        downstream_id: minimax
        output_model_id: MiniMax-M3
        - id: alias-deepseek-pro
        downstream_id: deepseek
        output_model_id: deepseek-v4-pro
  - input_model_id: claude-sonnet.*
    is_regex: true
    announced_names:
        - claude-sonnet
        - claude-sonnet-5
    options:
        - id: alias-llama-cpp-qwen-instruct
        downstream_id: llama-cpp
        output_model_id: qwen3.8:27b:instruct
        - id: alias-deepseek-flash
        downstream_id: deepseek
        output_model_id: deepseek-flash
        - id: alias-minimax-m2-7
        downstream_id: minimax
        output_model_id: MiniMax-M2.7
  - input_model_id: claude-haiku.*
    is_regex: true
    announced_names:
        - claude-haiku
        - claude-haiku-4-5
    options:
        - id: alias-minimax-m2-5
        downstream_id: minimax
        output_model_id: MiniMax-M2.5

Restart Tresor to apply the changes in yaml.

If a not-announced name like claude-opus-4-8 requests Tresor, the most precisely matched alias will still handle it (in this case, claude-opus.*). Optional announced names does not limit the capability of regex alias group's model name matching.

2. Configure Claude for Microsoft 365

Launch one of the office apps (Word, Excel, PowerPoint, or Outlook), click Cloud provider or gateway

In Gateway section:

Field	Value
Gateway URL	http://127.0.0.1:11510
Token	One of your Tresor API key in proxy_api_keys field (e.g., sk-proxy-123)

Click Continue. It will test the connectivity of all models that starts with `claude-, so make sure they are reachable. Once succeeded:

All other office apps will synchronize this setting, so you don't need to configure others one by one.

3. Hot-switch from the web UI

Open http://127.0.0.1:11510 in a browser, go to the Aliases tab, and click any sibling option card to make it active. Claude for Microsoft 365's next request will be routed to the new downstream — no restart of either Tresor or Claude for Microsoft 365 is required. 🎉

For example, flip claude-sonnet from deepseek-flash to MiniMax-M2.7 with a single click, and the agent immediately starts using MiniMax on the following turn.

📚 See also

• Claude Microsoft 365 Docs