How to integrate Google Calendar MCP with Mastra AI

Connect Mastra AI to Google Calendar MCP. Create a meeting with the marketing team, list all events scheduled for next week, and more using natural language, with authentication handled for you.

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Google Calendar

Oauth2

Google Calendar is a time management service for scheduling meetings, events, and reminders. It streamlines personal and team organization with integrated notifications and sharing options.

47 Tools7 Triggers

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Introduction

This guide walks you through connecting Google Calendar to Mastra AI using the Composio tool router. By the end, you'll have a working Google Calendar agent that can create a meeting with the marketing team, list all events scheduled for next week, delete tomorrow’s canceled event from your calendar through natural language commands.

This guide will help you understand how to give your Mastra AI agent real control over a Google Calendar account through Composio's Google Calendar MCP server.

Before we dive in, let's take a quick look at the key ideas and tools involved.

Also integrate Google Calendar with

TL;DR

Here's what you'll learn:

Set up your environment so Mastra, OpenAI, and Composio work together
Create a Tool Router session in Composio that exposes Google Calendar tools
Connect Mastra's MCP client to the Composio generated MCP URL
Fetch Google Calendar tool definitions and attach them as a toolset
Build a Mastra agent that can reason, call tools, and return structured results
Run an interactive CLI where you can chat with your Google Calendar agent

What is Mastra AI?

Mastra AI is a TypeScript framework for building AI agents with tool support. It provides a clean API for creating agents that can use external services through MCP.

Key features include:

MCP Client: Built-in support for Model Context Protocol servers
Toolsets: Organize tools into logical groups
Step Callbacks: Monitor and debug agent execution
OpenAI Integration: Works with OpenAI models via @ai-sdk/openai

What is the Google Calendar MCP server, and what's possible with it?

The Google Calendar MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Google Calendar account. It provides structured and secure access to your calendars, events, availability, and sharing settings, so your agent can schedule meetings, find events, check availability, update plans, and manage calendars on your behalf.

Event scheduling and updates: Have your agent create events with set times or durations, change event details, and delete canceled plans.
Event search and review: Instruct your agent to find events by keywords or time range, retrieve event details, and review instances of recurring events.
Availability checks: Let the agent check busy periods across one or more calendars before arranging a meeting.
Calendar organization: Direct your agent to create, rename, update, delete, add, or remove calendars from your calendar list.
Calendar access management: Have your agent create, review, or remove calendar access rules to control sharing.

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

Composio's Composio SDK helps agents find the right tools for a task at runtime. You can plug in multiple toolkits (like Gmail, HubSpot, and GitHub), and the agent will identify the relevant app and action to complete multi-step workflows. This can reduce token usage and improve the reliability of tool calls. Read more here: Getting started with Composio SDK

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Composio SDK works

The Composio SDK follows a three-phase workflow:

Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Step by step09 STEPS

Prerequisites

Before starting, make sure you have:

Node.js 18 or higher
A Composio account with an active API key
An OpenAI API key
Basic familiarity with TypeScript

Getting API Keys for OpenAI and Composio

OpenAI API Key

Go to the OpenAI dashboard and create an API key.
You need credits or a connected billing setup to use the models.
Store the key somewhere safe.

Composio API Key

Log in to the Composio dashboard.
Go to Settings and copy your API key.
This key lets your Mastra agent talk to Composio and reach Google Calendar through MCP.

Install dependencies

bash

npm install @composio/core @mastra/core @mastra/mcp @ai-sdk/openai dotenv

Install the required packages.

What's happening:

@composio/core is the Composio SDK for creating MCP sessions
@mastra/core provides the Agent class
@mastra/mcp is Mastra's MCP client
@ai-sdk/openai is the model wrapper for OpenAI
dotenv loads environment variables from .env

Set up environment variables

bash

COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key_here

Create a .env file in your project root.

What's happening:

COMPOSIO_API_KEY authenticates your requests to Composio
COMPOSIO_USER_ID tells Composio which user this session belongs to
OPENAI_API_KEY lets the Mastra agent call OpenAI models

Import libraries and validate environment

typescript

import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({
  apiKey: composioAPIKey as string,
});

What's happening:

dotenv/config auto loads your .env so process.env.* is available
openai gives you a Mastra compatible model wrapper
Agent is the Mastra agent that will call tools and produce answers
MCPClient connects Mastra to your Composio MCP server
Composio is used to create a Tool Router session

Create a Tool Router session for Google Calendar

typescript

async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["googlecalendar"],
    },
  );

  const composioMCPUrl = session.mcp.url;
  console.log("Google Calendar MCP URL:", composioMCPUrl);

What's happening:

create spins up a short-lived MCP HTTP endpoint for this user
The toolkits array contains "googlecalendar" for Google Calendar access
session.mcp.url is the MCP URL that Mastra's MCPClient will connect to

Configure Mastra MCP client and fetch tools

typescript

const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      nasdaq: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

console.log("Fetching MCP tools from Composio...");
const composioTools = await mcpClient.getTools();
console.log("Number of tools:", Object.keys(composioTools).length);

What's happening:

MCPClient takes an id for this client and a list of MCP servers
The headers property includes the x-api-key for authentication
getTools fetches the tool definitions exposed by the Google Calendar toolkit

Create the Mastra agent

typescript

const agent = new Agent({
    name: "googlecalendar-mastra-agent",
    instructions: "You are an AI agent with Google Calendar tools via Composio.",
    model: "openai/gpt-5",
  });

What's happening:

Agent is the core Mastra agent
name is just an identifier for logging and debugging
instructions guide the agent to use tools instead of only answering in natural language
model uses openai("gpt-5") to configure the underlying LLM

Set up interactive chat interface

typescript

let messages: AiMessageType[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end.\n");

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  prompt: "> ",
});

rl.prompt();

rl.on("line", async (userInput: string) => {
  const trimmedInput = userInput.trim();

  if (["exit", "quit", "bye"].includes(trimmedInput.toLowerCase())) {
    console.log("\nGoodbye!");
    rl.close();
    process.exit(0);
  }

  if (!trimmedInput) {
    rl.prompt();
    return;
  }

  messages.push({
    id: crypto.randomUUID(),
    role: "user",
    content: trimmedInput,
  });

  console.log("\nAgent is thinking...\n");

  try {
    const response = await agent.generate(messages, {
      toolsets: {
        googlecalendar: composioTools,
      },
      maxSteps: 8,
    });

    const { text } = response;

    if (text && text.trim().length > 0) {
      console.log(`Agent: ${text}\n`);
        messages.push({
          id: crypto.randomUUID(),
          role: "assistant",
          content: text,
        });
      }
    } catch (error) {
      console.error("\nError:", error);
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    console.log("\nSession ended.");
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(1);
});

What's happening:

messages keeps the full conversation history in Mastra's expected format
agent.generate runs the agent with conversation history and Google Calendar toolsets
maxSteps limits how many tool calls the agent can take in a single run
onStepFinish is a hook that prints intermediate steps for debugging

Complete Code

Here's the complete code to get you started with Google Calendar and Mastra AI:

typescript

import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({ apiKey: composioAPIKey as string });

async function main() {
  const session = await composio.create(composioUserID as string, {
    toolkits: ["googlecalendar"],
  });

  const composioMCPUrl = session.mcp.url;

  const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      googlecalendar: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "googlecalendar-mastra-agent",
    instructions: "You are an AI agent with Google Calendar tools via Composio.",
    model: "openai/gpt-5",
  });

  let messages: AiMessageType[] = [];

  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: "> ",
  });

  rl.prompt();

  rl.on("line", async (input: string) => {
    const trimmed = input.trim();
    if (["exit", "quit"].includes(trimmed.toLowerCase())) {
      rl.close();
      return;
    }

    messages.push({ id: crypto.randomUUID(), role: "user", content: trimmed });

    const { text } = await agent.generate(messages, {
      toolsets: { googlecalendar: composioTools },
      maxSteps: 8,
    });

    if (text) {
      console.log(`Agent: ${text}\n`);
      messages.push({ id: crypto.randomUUID(), role: "assistant", content: text });
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main();

Conclusion

You've built a Mastra AI agent that can interact with Google Calendar through Composio's Tool Router. You can extend this further by:

Adding other toolkits like Gmail, Slack, or GitHub
Building a web-based chat interface around this agent
Using multiple MCP endpoints to enable cross-app workflows

TOOLS & TRIGGERS

Supported Tools and Triggers

Every Google Calendar action and event your agent gets out of the box.

Delete ACL Rule

Deletes an access control rule from a Google Calendar.

Get ACL Rule

Retrieves a specific access control rule for a calendar.

Create ACL Rule

Creates an access control rule for a calendar.

List ACL Rules

Retrieves the list of access control rules (ACLs) for a specified calendar, providing the necessary 'rule_id' values required for updating specific ACL rules.

Patch ACL Rule

Updates an existing access control rule for a calendar using patch semantics (partial update).

Update ACL Rule

Updates an access control rule for the specified calendar.

Watch ACL Changes

Tool to watch for changes to ACL resources.

Batch Events

Execute up to 1000 event mutations (create/patch/delete) in one Google Calendar HTTP batch request with per-item status/results.

Remove Calendar from List

Tool to remove a calendar from the user's calendar list.

Get Single Calendar by ID

Retrieves metadata for a SINGLE specific calendar from the user's calendar list by its calendar ID.

Insert Calendar into List

Inserts an existing calendar into the user's calendar list, making it visible in the UI.

Patch Calendar List Entry

Updates an existing calendar on the user's calendar list using patch semantics.

Update Calendar List Entry

Updates a calendar list entry's display/subscription settings (color, visibility, reminders, selection) for the authenticated user — does not modify the underlying calendar resource (title, timezone, etc.

Watch Calendar List

Watch for changes to CalendarList resources using push notifications.

Delete Calendar

Deletes a secondary calendar that you own or have delete permissions on.

Update Calendar

Full PUT-style update that overwrites all calendar metadata fields; unspecified optional fields are cleared.

Stop Channel

Tool to stop watching resources through a notification channel.

Clear Calendar

Clears a primary calendar by deleting all events from it.

Get Color Definitions

Returns the color definitions for calendars and events.

Create a new calendar

Creates a new secondary Google Calendar with the specified title and optional settings.

Create Event

Creates a timed event using start_datetime and either end_datetime or duration fields, or an all-day event using an inclusive start_date and exclusive end_date.

Delete event

Deletes an event from the specified calendar.

Create a calendar

Creates a new, empty Google Calendar with the specified title (summary).

Get Event

Retrieves a SINGLE event by its unique event_id (REQUIRED).

Import Event

Tool to import an event as a private copy to a calendar.

Get Event Instances

Returns instances of the specified recurring event.

List Events

Lists or incrementally synchronizes events from one calendar, defaulting to the connected user's primary calendar.

List Events from All Calendars

Return a unified event list across all calendars in the user's calendar list for a given time range.

Move Event

Moves an event to another calendar, i.

Watch Events

Watch for changes to Events resources.

Find event

Finds events in a specified Google Calendar using text query, time ranges (event start/end, last modification), and event types.

Find free slots

Finds both free and busy time slots in Google Calendars for specified calendars within a defined time range.

Query Calendar Availability

Queries raw busy intervals for one or more calendars or groups over an exact time range.

Get Google Calendar

Gets canonical metadata for one Google Calendar, defaulting to the authenticated user's primary calendar.

Get current date and time

Gets the current date and time, allowing for a specific timezone offset.

Get Current Google Calendar User

Identifies the Google user connected to Calendar from the primary calendar resource.

List Buildings

Lists all buildings for a Google Workspace customer account with full details including addresses, coordinates, and floor names.

List Calendar Resources

Retrieves calendar resources (such as conference rooms) from a Google Workspace domain using the Admin SDK Directory API.

List Google Calendars

Lists calendars accessible through the connected user's CalendarList, returning IDs and user-specific metadata such as access role, color, visibility, selection, and reminders.

Patch Calendar

Partially updates (PATCHes) an existing Google Calendar, modifying only the fields provided.

Patch Event

Update specified fields of an existing event in a Google Calendar using patch semantics (array fields like `attendees` are fully replaced if provided); ensure the `calendar_id` and `event_id` are valid and the user has write access to the calendar.

Quick Add Event

Parses natural language text to quickly create a basic Google Calendar event with its title, date, and time, suitable for simple scheduling; does not support direct attendee addition or recurring events, and `calendar_id` must be valid if not 'primary'.

Remove attendee from event

Removes an attendee from a specified event in a Google Calendar; the calendar and event must exist.

Get Calendar Setting

Tool to return a single user setting for the authenticated user.

List Settings

Returns all user settings for the authenticated user.

Watch Settings

Watch for changes to Settings resources.

Update Google event

Updates an existing event in Google Calendar.

FRAMEWORKS

How to build Google Calendar MCP Agent with another framework

Claude Code

Use Google Calendar MCP with Claude Code

Cursor

Use Google Calendar MCP with Cursor

ChatGPT

Use Google Calendar MCP with ChatGPT

Claude Cowork

Use Google Calendar MCP with Claude Cowork

Antigravity

Use Google Calendar MCP with Antigravity

OpenAI Agents SDK

Use Google Calendar MCP with OpenAI Agents SDK

Claude Agent SDK

Use Google Calendar MCP with Claude Agent SDK

Grok Bot

Use Google Calendar MCP with Grok Bot

Muse

Use Google Calendar MCP with Muse

Codex

Use Google Calendar MCP with Codex

Kimi Code

Use Google Calendar MCP with Kimi Code

Grok Build

Use Google Calendar MCP with Grok Build

VS Code

Use Google Calendar MCP with VS Code

OpenCode

Use Google Calendar MCP with OpenCode

OpenClaw

Use Google Calendar MCP with OpenClaw

Hermes

Use Google Calendar MCP with Hermes

Atomic Agent

Use Google Calendar MCP with Atomic Agent

CLI

Use Google Calendar MCP with CLI

Google ADK

Use Google Calendar MCP with Google ADK

LangChain

Use Google Calendar MCP with LangChain

Vercel AI SDK

Use Google Calendar MCP with Vercel AI SDK

LlamaIndex

Use Google Calendar MCP with LlamaIndex

CrewAI

Use Google Calendar MCP with CrewAI

Pydantic AI

Use Google Calendar MCP with Pydantic AI

AutoGen

Use Google Calendar MCP with AutoGen

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Bart is the Bay Area Rapid Transit system, providing fast public transportation across the San Francisco Bay Area. It helps commuters and travelers get real-time schedule info, plan routes, and stay updated on service changes.

Blue Pillow Hotels & Stays

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Blue Pillow Hotels & Stays is a hotel and stay discovery platform offering live offers, recommendations, and booking handoff. It helps surface and compare real-time deals and validate bookings for smoother reservations.

FAQ

Frequently asked questions

With a standalone Google Calendar MCP server, the agents and LLMs can only access a fixed set of Google Calendar tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Google Calendar and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. Mastra AI fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Google Calendar tools.

Yes, absolutely. You can configure which Google Calendar scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Google Calendar data and credentials are handled as safely as possible.

Start with Google Calendar.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Google Calendar tool your agent needs.Free to start.

Start building

How to integrate Google Calendar MCP with Mastra AI

Connect Google Calendar without auth hassles

Introduction

Also integrate Google Calendar with

TL;DR

What is Mastra AI?

What is the Google Calendar MCP server, and what's possible with it?

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

How the Composio SDK works

Step-by-step Guide

Prerequisites

Getting API Keys for OpenAI and Composio

Install dependencies

Set up environment variables

Import libraries and validate environment

Create a Tool Router session for Google Calendar

Configure Mastra MCP client and fetch tools

Create the Mastra agent

Set up interactive chat interface

Complete Code

Conclusion

Supported Tools and Triggers

How to build Google Calendar MCP Agent with another framework

Claude Code

Cursor

ChatGPT

Claude Cowork

Antigravity

OpenAI Agents SDK

Claude Agent SDK

Grok Bot

Muse

Codex

Kimi Code

Grok Build

VS Code

OpenCode

OpenClaw

Hermes

Atomic Agent

CLI

Google ADK

LangChain

Vercel AI SDK

LlamaIndex

CrewAI

Pydantic AI

AutoGen

Explore Other Toolkits

Apaleo

Appointo

Bart

Blue Pillow Hotels & Stays

Frequently asked questions

What are the differences in Tool Router MCP and Google Calendar MCP?+

Can I use Tool Router MCP with Mastra AI?+

Can I manage the permissions and scopes for Google Calendar while using Tool Router?+

How safe is my data with Composio Tool Router?+

Start with Google Calendar.It takes 30 seconds.