outlook-desktop-mcp 0.1.0

Run this on Windows and get Outlook Desktop as an MCP server. No Graph API, no Entra app registration — just your local Outlook.

outlook-desktop-mcp

Run this on Windows and get Outlook Desktop as an MCP server. No Microsoft Graph API, no Entra app registration, no OAuth tokens — just your local Outlook.

Uses COM automation to talk directly to your running Outlook Desktop (Classic) instance, inheriting whatever authentication you already have.

MCP Client (Claude Code, etc.)
    |
    | stdio (JSON-RPC)
    v
outlook-desktop-mcp (Python)
    |
    | COM automation (MSOUTL.OLB)
    v
Outlook Desktop (Classic) — OUTLOOK.EXE
    |
    | Your existing auth session
    v
Exchange Online / Microsoft 365

Requirements

• Windows (COM automation is Windows-only)
• Outlook Desktop (Classic) — OUTLOOK.EXE, not the new olk.exe
• Python 3.12+
• Outlook must be running when the MCP server starts

Install

pip install outlook-desktop-mcp

Or from source:

git clone https://github.com/aaanerud/outlook-desktop-mcp.git
cd outlook-desktop-mcp
python -m venv .venv
.venv\Scripts\activate
pip install pywin32 "mcp[cli]" -e .
python .venv\Scripts\pywin32_postinstall.py -install

Register with Claude Code

claude mcp add outlook-desktop -- outlook-desktop-mcp

Or if installed from source:

claude mcp add outlook-desktop -- powershell.exe -Command "& 'C:\path\to\outlook-desktop-mcp.cmd' mcp"

Then in any Claude Code session, the 9 email tools are available automatically.

Available Tools

Tool	What it does
send_email	Send email via your default Outlook profile
list_emails	List recent emails from any folder
read_email	Read full email by ID or subject search
mark_as_read	Mark an email as read
mark_as_unread	Mark an email as unread
move_email	Move email to archive or any folder
reply_email	Reply or reply-all, preserving thread
list_folders	List folder hierarchy with item counts
search_emails	Full-text search on subject and body

How it works

The server runs a dedicated COM thread (STA apartment) that holds the Outlook.Application object. The async MCP event loop dispatches tool calls to this thread via a queue, so COM threading rules are respected and the MCP protocol never blocks.

All tool descriptions are written for LLM consumption — when Claude Code discovers the tools, it knows exactly how to use each one (what arguments to pass, what formats to expect, edge cases to watch for).

Extending

The architecture supports adding more Outlook modules. Planned:

• Calendar — events, meetings, scheduling
• Contacts — address book lookups
• Tasks — to-do items

Add new @mcp.tool() functions in server.py using the same bridge.call() pattern.

Why not Microsoft Graph?

Graph API requires an Entra (Azure AD) app registration, admin consent for mail permissions, OAuth token management, and tenant configuration. For a local developer tool that just wants to send and read email, that's massive overhead.

COM automation requires: Outlook is open. That's it.