MCP Server Setup Guide

Connect Calendrz to your
AI assistant.

Step-by-step instructions for Claude.ai and ChatGPT. No API keys. No manual configuration. Just a URL and a sign-in.

Under 2 minutes 🔒 OAuth 2.1 secured Works with Claude & ChatGPT

Before you start

Make sure you have the following before connecting your AI assistant.

Requirements

  • A Calendrz account at app.calendrz.com
  • At least two connected accounts configured in your Calendrz profile
  • Access to Claude.ai settings, ChatGPT settings, or another MCP-compatible client

💡 New to Calendrz? Create a free account at app.calendrz.com, connect your Google or Microsoft calendars, and come back here to set up your AI assistant.

The MCP server URL

This is the single URL you'll enter in any AI assistant to connect it to your Calendrz account.

MCP Server URL
https://app.calendrz.com/mcp

The AI assistant will automatically discover OAuth metadata from this endpoint. No other configuration is needed.

Connect Claude.ai

Claude.ai supports custom MCP connectors natively via its Connectors settings panel.

1

Open Claude Settings

Go to claude.ai → click your profile icon → SettingsConnectors (also labelled Integrations in some versions)

2

Add a Custom Connector

Click Add Custom Connector. You will be prompted to enter a server URL.

3

Enter the Calendrz MCP URL

Paste: https://app.calendrz.com/mcp
Claude will automatically discover the available tools and OAuth configuration.

4

Authorize

Click Authorize. You'll be redirected to Calendrz to sign in with your Google or Microsoft account. This is the same login you use for app.calendrz.com.

5

Done — start talking

Once authorized, Calendrz will appear as an active connector. Open a new conversation and try: "Show me my calendar events for next week."

Connect ChatGPT

ChatGPT supports MCP connections via its Connected Apps panel.

1

Open ChatGPT Settings

Go to chatgpt.com → click your profile → SettingsConnected Apps

2

Add a Connection

Click Add Connection and select the option to enter a custom server URL.

3

Enter the Calendrz MCP URL

Paste: https://app.calendrz.com/mcp
ChatGPT will discover tools and OAuth configuration automatically.

4

Follow the OAuth flow

Sign in with the Google or Microsoft account linked to your Calendrz profile. Authorization is handled securely via OAuth 2.1.

5

Done — start a conversation

Calendrz tools are now available. Try: "What calendars do I have connected in Calendrz?"

Other MCP clients

Any MCP-compatible client can connect to the Calendrz server. The server uses standard Streamable HTTP transport and OAuth 2.1 Dynamic Client Registration, so no manual credential setup is required.

OAuth Metadata Endpoint
https://app.calendrz.com/.well-known/oauth-authorization-server
Manual Client Registration (for testing)
curl -X POST https://app.calendrz.com/oauth2/register \
  -H 'Content-Type: application/json' \
  -d '{
    "redirect_uris": ["https://your-app.com/callback"],
    "client_name": "Your App"
  }'

How authentication works

Calendrz uses OAuth 2.1 with the authorization code grant flow. Here's what happens behind the scenes when you connect your AI assistant.

Discovery

The AI assistant fetches OAuth metadata from /.well-known/oauth-authorization-server to discover endpoints automatically.

Dynamic client registration

The AI platform registers itself automatically via POST /oauth2/register (RFC 7591). No manual credential setup required.

Authorization

You're redirected to /oauth2/authorize where you sign in with your existing Google or Microsoft account.

Token issuance

Calendrz issues a short-lived JWT access token (60 min) and a refresh token (30 days). Your Google/Microsoft credentials are never shared with the AI assistant.

MCP tool calls

All subsequent requests include Authorization: Bearer <token>. Tokens are refreshed automatically in the background.

Troubleshooting

Common issues and how to resolve them.

The connector URL isn't being accepted
Make sure you're entering the full URL including https://: https://app.calendrz.com/mcp. Some clients require the trailing path — do not shorten it to just app.calendrz.com.
I'm being asked for an API key but there isn't one
Calendrz uses OAuth 2.1, not API keys. If your client is asking for an API key, look for an "OAuth" or "Sign in" option instead. Both Claude and ChatGPT handle this automatically via their connector flows.
Authorization redirects to a blank page
This usually means your Calendrz account session has expired. Open app.calendrz.com in a new tab, sign in, then retry the authorization from your AI assistant's settings.
The AI says it can't find any tools
Try disconnecting and reconnecting the Calendrz connector. If the problem persists, ensure your Calendrz profile has at least two connected accounts — a profile with no connected accounts may return limited tool availability.
My events aren't showing up
The get_events tool reads from your connected calendar accounts. If you've recently added a new account, try asking your AI assistant to trigger a sync first: "Sync my calendars now."