Microsoft Advertising MCP Connector

Standalone True Model B MCP server for Claude.ai Custom Connectors. One operator can connect multiple Microsoft accounts. Each connection can see multiple Microsoft Advertising customers and advertising accounts.

This is not part of the Google All-in-One connector. It has no runtime dependency on that project, no shared Firestore collections, and no shared OAuth tokens.

Claude.ai
   │  MCP OAuth 2.1
   ▼
operatorId
   ├── Microsoft Connection A → customers → advertising accounts → campaigns / reports
   ├── Microsoft Connection B
   └── Microsoft Connection C

MCP JWT sub is always the internal operatorId. Microsoft OpenID sub lives only on bing_mcp_microsoft_connections.microsoftSubjectId. Email is display metadata, never an authorization key.

Architecture

• Next.js 15 App Router + mcp-handler Streamable HTTP at /mcp

• MCP OAuth 2.1 with PKCE S256, DCR, and Claude CIMD

• Microsoft Entra authorization-code flow (common tenant)

• Microsoft Advertising REST v13 (not SOAP)

• Named Firestore database bing-mcp-v1

• AES-256-GCM refresh-token encryption at rest

• Cloud Run (stateless; listen on $PORT)

Related MCP server: Bing Ads MCP Server

Credentials (these are different things)

Environment

Copy .env.example to .env. Never commit .env.

Required:

APP_BASE_URL
MICROSOFT_CLIENT_ID
MICROSOFT_CLIENT_SECRET
MICROSOFT_REDIRECT_URI
MICROSOFT_ADS_DEVELOPER_TOKEN
MCP_TOKEN_SECRET
OAUTH_STATE_SECRET
TOKEN_ENCRYPTION_KEY
FIRESTORE_PROJECT_ID
FIRESTORE_DATABASE_ID=bing-mcp-v1

FIRESTORE_DATABASE_ID must be bing-mcp-v1. Startup rejects (default) and gconnect-mcp-all-v1.

Microsoft Entra app registration

1. Open Microsoft Entra app registrations.

2. Create a registration.

3. Supported account types: Accounts in any organizational directory and personal Microsoft accounts (so common works).

4. Add a Web redirect URI: {APP_BASE_URL}/oauth/microsoft/callback (local example: http://localhost:3000/oauth/microsoft/callback).

5. Create a client secret. Store it in MICROSOFT_CLIENT_SECRET.

6. API permissions: Microsoft Advertising delegated scope https://ads.microsoft.com/msads.manage. Also request openid, profile, email, and offline_access.

7. Grant admin consent if your tenant requires it.

Official guides:

• Authentication with OAuth

• Request user consent

Developer token

Get a Microsoft Advertising developer token from Microsoft Advertising Developer Settings. Sandbox tokens can be self-issued; production tokens require Microsoft approval.

This token is an application credential. It is sent as the DeveloperToken header on Advertising REST calls. It is never stored per operator and must never appear in MCP output or logs.

Local development

npm install
npm test
npm run typecheck
npm run dev

• Health: GET http://localhost:3000/health

• MCP: http://localhost:3000/mcp

• Microsoft callback: http://localhost:3000/oauth/microsoft/callback

Add the Custom Connector in Claude.ai pointing at {APP_BASE_URL}/mcp. Claude completes MCP OAuth, then the server redirects the browser to Microsoft login. After consent, continue back to Claude.

Firestore locally: either Application Default Credentials (gcloud auth application-default login) plus FIRESTORE_PROJECT_ID, or FIRESTORE_EMULATOR_HOST.

MCP tools (V1, read-only)

Connections: get_operator, list_microsoft_connections, get_microsoft_connection, start_microsoft_connection, disconnect_microsoft_connection

Customers / accounts: list_microsoft_customers, get_microsoft_customer, list_microsoft_accounts, get_microsoft_account

Entities: list_campaigns, get_campaign, list_ad_groups, get_ad_group, list_ads, get_ad, list_keywords, get_keyword

Reports (official Reporting API, async submit/poll/download): get_account_performance, get_campaign_performance, get_ad_group_performance, get_keyword_performance

If the same advertising account is visible through more than one Microsoft connection, the server returns an ambiguity error and asks for connectionId. It never guesses.

Firestore collections

Named database: bing-mcp-v1

• bing_mcp_operators

• bing_mcp_microsoft_connections

• bing_mcp_connection_uniques ({operatorId}_{microsoftSubjectId})

• bing_mcp_microsoft_customers

• bing_mcp_microsoft_accounts

• bing_mcp_oauth_transactions

• bing_mcp_sessions

Cloud Run

Cloud Run ingress must be unauthenticated. Authentication is MCP JWT, not Cloud IAM.

The Cloud Run service account needs Firestore access on the named database (roles/datastore.user is typical). Use Application Default Credentials. Do not commit a service-account JSON file.

.\scripts\cloud-run-setup.ps1 -ProjectId YOUR_PROJECT
.\scripts\cloud-run-deploy.ps1 -ProjectId YOUR_PROJECT
.\scripts\cloud-run-set-env.ps1 -ProjectId YOUR_PROJECT -AppBaseUrl https://... -MicrosoftClientId ... -MicrosoftClientSecret ... -McpTokenSecret ... -OauthStateSecret ... -TokenEncryptionKey ... -MicrosoftAdsDeveloperToken ...

Then add {APP_BASE_URL}/oauth/microsoft/callback to the Entra app and add the Claude Custom Connector at {APP_BASE_URL}/mcp.

Service timeout is 300 seconds so async reports can finish.

Security

Never exposed through MCP or logs: access tokens, refresh tokens, client secrets, developer token, encryption keys, authorization codes.

Authorization uses operatorId + connectionId + Microsoft IDs. Names and emails are not authorization identifiers.

V2 (not implemented)

Campaign create/update/pause, ad group and ad writes, keyword writes, budget updates.

Tests

npm test

Automated tests cover MCP JWT identity, Microsoft OAuth state/exchange/refresh/invalid_grant, operator isolation, multi-connection, same Microsoft identity across operators, ambiguous account rejection, report CSV parsing, header rules, and secret redaction.

Live Claude, Microsoft login, and Cloud Run paths require your Entra app, developer token, and GCP project.