M365 Assistant MCP Server

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MCP server connecting Claude to Microsoft 365

How to install ↓ Compare GitHub source repository ↗

Category: Collaboration #44 of 55
Stars: ★ 443 Popular
Transport: stdio (local process)
Runtime: Node.js 14.0.0+
Credentials: API key / credential required
Last commit: 6 months ago ⚠
Tools: 28

42FMRS · D

This server is feature-rich, covering Outlook, OneDrive, and Power Automate, but setup is complex, requiring Azure AD registration and broad permissions. Suitable for developers familiar with Azure, but security configuration should be considered.

Strongest · Documentation 13/20 Weakest · Maintenance 4/20

Reliability

5/20

Security and permissions

9/20

Maintenance

4/20

Documentation

13/20

Setup experience

11/20

Why each score

Reliability 5/20: Evidence: only the README and repository metadata were supplied — no source files, no server manifest, no CI or test logs to verify. The README's modular directory structure, tool list and test mode are internally coherent, and it claims Jest tests (npm test), but those are assertions, not evidence. Deductions: 25 open issues and zero execution evidence; per static calibration (no real CI workflows plus committed tests, reliability cannot exceed 12) and the missing-evidence rule, the key paths are only 'plausible' — clean startup, handshake and tool behavior cannot be confirmed.
Security and permissions 9/20: Evidence: the README documents OAuth 2.0 delegated permissions close to least privilege (Read/ReadWrite for Mail, Calendars, Files plus offline_access and User.Read), a localhost:3333 redirect URI, and an explicit warning to use the client secret VALUE rather than the Secret ID. Deductions: tokens are stored in plaintext at ~/.outlook-mcp-tokens.json with no mention of encryption; no confirmation mechanism is documented for destructive or high-impact tools (delete-event, onedrive-delete, send-email, flow-run); data-flow boundaries and retention are not fully disclosed. No red line is triggered (no malware, credential theft, exfiltration, or real secrets in examples).
Maintenance 4/20: Evidence: the repository is not archived and has many stars, but stars are a discovery signal only and add no points. Deductions: license is unknown and the README mentions no license file or terms; there is no evidence of releases, commit cadence, dependency updates, or a security-response channel; 25 open issues. A missing license is a major governance gap and forces a low maintenance score.
Documentation 13/20: Evidence: the README is well-layered — install steps, Azure app registration, permission list, .env and Claude Desktop config JSON examples, auth flow, troubleshooting, testing and extension guidance, plus disclosed Power Automate limitations. Deductions: the tool table only has one-line descriptions with no per-tool parameter schemas; no rate-limit, cost, or retention information; the dual MS_CLIENT_ID / OUTLOOK_CLIENT_ID naming is confusing and a hidden assumption.
Setup experience 11/20: Evidence: the install path is clear and complete (npm install → Azure registration and permissions → .env config → Claude Desktop config → start auth-server → authenticate tool), with client config examples and a port-conflict workaround. Deductions: no CI or test execution evidence, so static calibration caps setup at 15; the flow depends on manual Azure configuration, a separate auth server and a local token file — many steps and somewhat fragile.

Static review · not runListed 2026-08-07

Read the FMRS scoring method →

Fit and risk

What it can accessUses the networkChanges third-party account data

Best for

Developers needing integration between Microsoft 365 and AI assistants
Individuals wanting natural language control of Outlook and OneDrive
Teams automating email and calendar management

Not for

Organizations with strict security requirements against third-party servers
Users needing deep integration with Microsoft Teams or SharePoint (not supported)
Beginners wanting a plug-and-play solution without Azure configuration

Required permissions

Microsoft Graph delegated permissions: offline_access, User.Read, Mail.ReadWrite, Mail.Send, Calendars.ReadWrite, Files.ReadWrite
Power Automate API scope (optional): https://service.flow.microsoft.com//.default
Local file system: tokens stored in ~/.outlook-mcp-tokens.json

Risks and side effects

OAuth tokens stored in plaintext locally, risk of exposure
Azure app registration required, misconfiguration can break service
Power Automate integration limited to solution-aware flows with manual triggers
Third-party server may introduce supply chain risk

Setup

Before you start

Runtime：Node.js 14.0.0+

OUTLOOK_CLIENT_ID required The Application (client) ID from your Azure Portal app registration, used in the Claude Desktop config.

OUTLOOK_CLIENT_SECRET requiredsecret The client secret VALUE (not the Secret ID) generated under Azure 'Certificates & secrets'; keep it secret.

MS_CLIENT_SECRET optionalsecret Same value as OUTLOOK_CLIENT_SECRET, used in the .env file; must be the secret VALUE.

Other optional settings (3)

USE_TEST_MODE optional Set to true to use mock data for testing without real API calls; defaults to false.

MS_CLIENT_ID optional Same value as OUTLOOK_CLIENT_ID, used in the .env file for the Azure app client ID.

MS_TENANT_ID optional Your Azure app's tenant ID; set it for single-tenant apps to avoid /common endpoint errors.

Clone the repository and install dependencies: npm install.
Register an app in Azure Portal (set redirect URI to http://localhost:3333/auth/callback).
Add required API permissions (Mail.Read, Mail.Send, Calendars.ReadWrite, etc.).
Copy .env.example to .env and fill in Azure credentials.
Update Claude Desktop config to point to index.js.
Run npm run auth-server and use the authenticate tool to complete OAuth.
Optional: configure Power Automate additional permissions.

claude_desktop_config.json

{
  "mcpServers": {
    "m365-assistant": {
      "command": "node",
      "args": [
        "/path/to/outlook-mcp/index.js"
      ],
      "env": {
        "USE_TEST_MODE": "false",
        "OUTLOOK_CLIENT_ID": "your-client-id",
        "OUTLOOK_CLIENT_SECRET": "your-client-secret"
      }
    }
  }
}

Shown for Claude Desktop. Other clients may use a different file or key (VS Code uses "servers") — the configurator below converts it.

.vscode/mcp.json

{
  "servers": {
    "m365-assistant": {
      "command": "node",
      "args": [
        "/path/to/outlook-mcp/index.js"
      ],
      "env": {
        "USE_TEST_MODE": "false",
        "OUTLOOK_CLIENT_ID": "your-client-id",
        "OUTLOOK_CLIENT_SECRET": "your-client-secret"
      }
    }
  }
}

Goes in your project's .vscode/mcp.json (VS Code uses a "servers" key).

Terminal

claude mcp add m365-assistant -e USE_TEST_MODE=false -e OUTLOOK_CLIENT_ID=your-client-id -e OUTLOOK_CLIENT_SECRET=your-client-secret -- node /path/to/outlook-mcp/index.js

Run it in a terminal; replace any <…> placeholders with your own values first.

Generate and validate client config

Check that it works

After completing OAuth authentication, tools such as list-emails, send-email, and onedrive-list should appear in the client's tool list; a list-emails call returning real mail confirms the connection works.

Troubleshooting

Module errors: run `npm install`
Port 3333 in use: `npx kill-port 3333` and restart
Invalid client secret: use the secret VALUE, not the Secret ID
Authentication required: delete `~/.outlook-mcp-tokens.json` and re-authenticate

Things to try

Once connected, you can ask your AI assistant things like:

List my 10 most recent emails from the inbox
Search my emails for anything containing 'invoice'
Create a calendar event tomorrow at 3pm for a team meeting
List the files in my OneDrive reports folder

Tools 28

list-emails read-only

List recent emails from inbox

search-emails read-only

Search emails with filters

read-email read-only

Read email content

send-email destructive

Send a new email

mark-as-read writes

Mark email as read/unread

list-events read-only

List calendar events

create-event writes

Create calendar event

accept-event writes

Accept event invitation

Show 20 more tools

decline-event writes

Decline event invitation

delete-event destructive

Delete calendar event

list-folders read-only

List mail folders

create-folder writes

Create mail folder

move-emails writes

Move emails between folders

list-rules read-only

List inbox rules

create-rule writes

Create inbox rule

onedrive-list read-only

List files in a path

onedrive-search read-only

Search files by query

onedrive-download read-only

Get download URL

onedrive-upload writes

Upload small file (<4MB)

onedrive-upload-large writes

Chunked upload (>4MB)

onedrive-share writes

Create sharing link

onedrive-create-folder writes

Create folder

onedrive-delete destructive

Delete file or folder

flow-list-environments read-only

List Power Platform environments

flow-list read-only

List flows in environment

flow-run writes

Trigger a manual flow

flow-list-runs read-only

Get flow run history

flow-toggle writes

Enable/disable a flow

Use cases

Manage Outlook emails and calendar via natural language

Search, upload, and share files in OneDrive

Trigger and monitor Power Automate flows from Claude

Supported clients

Claude Desktop

Listed from the project's documentation, not tested by this site.

Overview

The M365 Assistant MCP Server is a Model Context Protocol (MCP) server that connects Claude with Microsoft 365 services through the Microsoft Graph API and Power Automate API. It supports Outlook email, calendar, folders, and rules; OneDrive file operations; and Power Automate flow control. Features OAuth 2.0 authentication, test mode, and modular design.

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Source revision 95d6ff2d2489 Data synced 2026-10-12 Read the FMRS scoring method