Helix

An open-source Model Context Protocol (MCP) server for Microsoft 365, built with .NET 10.

CI License: MIT .NET MCP

---

Overview

Helix is an MCP server that bridges AI agents with Microsoft 365. It exposes M365 services as MCP tools so AI models like Claude can read your email, send messages, manage attachments, and more — all through the standardized Model Context Protocol.

Built by SAIB Inc.

Install

One-line installer (macOS & Linux)

curl -fsSL https://raw.githubusercontent.com/SAIB-Inc/Helix/main/install.sh | bash

This downloads a self-contained binary to ~/.helix/bin/helix — no .NET SDK required.

To install a specific version:

HELIX_VERSION=0.1.0 curl -fsSL https://raw.githubusercontent.com/SAIB-Inc/Helix/main/install.sh | bash

Verify

helix --version

Prerequisites

You need an Azure AD app registration to authenticate with Microsoft 365.

1. Go to Azure Portal > App registrations and create a new registration
2. Set Supported account types to your preference (single tenant or multi-tenant)
3. Under Authentication, enable Allow public client flows (required for device code auth)
4. Under API permissions, add the following delegated permissions:
   • User.Read
   • Mail.Read, Mail.ReadWrite, Mail.Send
   • Calendars.Read, Calendars.ReadWrite
   • Sites.Read.All, Sites.ReadWrite.All
5. Note your Application (client) ID and Directory (tenant) ID

Configure

Set your Azure app credentials via environment variables:

export HELIX__ClientId="your-client-id"
export HELIX__TenantId="your-tenant-id"   # optional, defaults to "common"

Or create a .env file in your working directory:

HELIX__ClientId=your-client-id
HELIX__TenantId=your-tenant-id

Usage with Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "helix": {
      "command": "helix",
      "env": {
        "HELIX__ClientId": "your-client-id",
        "HELIX__TenantId": "your-tenant-id"
      }
    }
  }
}

If helix is not on your PATH, use the full path: ~/.helix/bin/helix

Available Tools

Authentication

Tool	Description
login	Start device code authentication flow
login-status	Check if authentication is complete
logout	Sign out and clear cached tokens
get-current-user	Get the authenticated user's profile

Mail

Tool	Description
list-mail-messages	List messages with filtering, search (KQL), and paging
get-mail-message	Get a full message by ID
send-mail	Send an email (supports file attachments)
delete-mail-message	Delete a message (moves to Deleted Items)
move-mail-message	Move a message to a different folder
update-mail-message	Update read status, importance, categories, or subject

Mail Drafts

Tool	Description
create-draft-message	Create a draft email in the Drafts folder
send-draft-message	Send an existing draft by ID

Mail Attachments

Tool	Description
list-mail-attachments	List attachments on a message
get-mail-attachment	Download an attachment to disk
add-mail-attachment	Attach a file from disk to a draft
delete-mail-attachment	Remove an attachment

Mail Folders

Tool	Description
list-mail-folders	List all mail folders with unread counts
list-mail-folder-messages	List messages in a specific folder

Calendar

Tool	Description
list-calendars	List all calendars
get-calendar-online-meeting-settings	Get allowed/default online meeting providers for diagnostics
list-calendar-events	List events with filtering and paging
get-calendar-event	Get a full event by ID
list-calendar-view	List events in a date/time range (expands recurring events)
create-calendar-event	Create a new event with attendees, location, online meeting
update-calendar-event	Update an existing event
delete-calendar-event	Delete an event
respond-calendar-event	Accept, decline, or tentatively accept an invitation

SharePoint — Sites

Tool	Description
search-sites	Search for SharePoint sites by keyword
get-site	Get a site by ID
list-site-lists	List all lists in a site
get-site-list	Get a list with column definitions

SharePoint — List Items

Tool	Description
list-list-items	List items with field values, filtering, and paging
get-list-item	Get a specific item with all fields
create-list-item	Create a new item with field values (JSON)
update-list-item	Update item fields
delete-list-item	Delete an item

SharePoint — Files

Tool	Description
list-site-drives	List document libraries in a site
list-drive-children	List files and folders (root or subfolder)
search-drive-items	Search files by name or content across a drive
get-drive-item	Get file/folder metadata
create-drive-folder	Create a new folder in a document library
upload-drive-item	Upload a file (from disk or base64)
download-drive-item	Download a file to disk

Roadmap

Service	Status
Mail	Available
Calendar	Available
SharePoint	Available
Contacts	Planned
OneDrive	Planned
Teams	Planned
Planner / To Do	Planned

Build from Source

If you prefer to build from source instead of using the installer:

git clone https://github.com/SAIB-Inc/Helix.git
cd Helix
dotnet build
dotnet run --project src/Helix.Stdio

Requires .NET 10 SDK.

Contributing

See docs/CONTRIBUTING.md for branch workflow, commit conventions, and design principles.

License

MIT — see LICENSE.

---

Built and maintained by SAIB Inc.