University Microsoft 365 Read-only MCP

A read-only Model Context Protocol server that exposes a fixed surface of read tools for university Microsoft 365 resources via a Power Automate HTTP-trigger intermediary. The current implementation covers the Outlook mailbox (three tools); other Microsoft 365 apps (Teams, OneDrive, etc.) are added as new features. See SPEC.md for the full specification.

Specification

Architecture

MCP Client
    ↓  MCP over Streamable HTTP (/mcp)
Remote MCP Server — Cloudflare Workers + Hono (this repo)
    ↓  HTTP POST { operation, requestId, args }
Power Automate — operation allowlist → fixed Graph endpoints, M365 auth
    ↓
Microsoft Graph — Outlook mailbox

• Read-only. Exactly three Outlook tools, three operations, fixed Graph endpoints. The server never authenticates to Graph and never calls Graph directly.

• Stateless. A fresh McpServer is created per request.

• Auth for /mcp is delegated to Cloudflare Access (OAuth) in front of the Worker; this app performs no auth itself.

Tools

Power Automate protocol

Request (POST JSON):

{ "operation": "list_messages | search_messages | get_message", "requestId": "<uuid>", "args": { ... } }

• list_messages → args: { top }

• search_messages → args: { query, top }

• get_message → args: { messageId }

Response (2xx):

{ "ok": true, "requestId": "<uuid>", "operation": "...", "data": { /* Graph response */ } }

The server normalizes data into the tool output schemas below.

Message shapes

type Recipient = { name: string; address: string }

type MessageSummary = {
  id: string; subject: string; from: Recipient
  receivedDateTime: string; hasAttachments: boolean
  importance: 'low' | 'normal' | 'high'; isRead: boolean
  bodyPreview: string
}

type MessageDetail = {
  id: string; subject: string; from: Recipient
  to: Recipient[]; cc: Recipient[]
  receivedDateTime: string; hasAttachments: boolean
  importance: 'low' | 'normal' | 'high'; isRead: boolean
  body: { contentType: 'text' | 'html'; content: string }
}

Related MCP server: M365 MCP

Requirements

• Bun

• A Cloudflare account with Wrangler authentication (for deployment)

• Cloudflare Access (OAuth) in front of the Worker to protect /mcp

• A Power Automate HTTP-trigger flow that accepts { operation, requestId, args } and proxies Microsoft Graph read calls (see SPEC §7)

Configuration

Set the required environment variables. For local development, copy .dev.vars.example to .dev.vars and fill in real values:

POWER_AUTOMATE_URL=https://prod-xxx.logic.azure.com/workflows/xxx/triggers/manual/paths/invoke

For production, set these as Worker secrets/vars (wrangler secret put).

Development

bun install
bun run dev          # local Worker (wrangler dev)

The MCP endpoint is served at /mcp (protected by Cloudflare Access OAuth in front of the Worker; this app performs no auth itself). A public info page is served at /.

Quality checks

bun run typecheck    # tsc --noEmit
bun run lint         # oxlint
bun run lint:types   # oxlint --type-aware
bun run format:check # oxfmt --check
bun run test         # vitest

Deploy

bun run deploy       # wrangler deploy