How to integrate Google Calendar MCP with Mastra AI

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.

Get started for freeGet a demo
Google Calendar logoGoogle 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.

44 Tools7 Triggers

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

ChatGPTOpenAI Agents SDKClaude Agent SDKClaude CodeClaude CoworkCodexOpenCodeCursorVS CodeOpenClawHermesCLIGoogle ADKLangChainVercel AI SDKLlamaIndexCrewAI

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 and events, so your agent can schedule meetings, create or modify events, list upcoming appointments, and manage calendars—all on your behalf.

  • Automated event creation and scheduling: Easily instruct your agent to add new events, meetings, or reminders with specific times, attendees, and details.
  • Event listing and agenda overview: Have your agent list all upcoming, past, or filtered events on any of your calendars to keep you on top of your schedule.
  • Calendar management and customization: Direct your agent to create new calendars, update calendar details, or even insert calendars into your list for better organization.
  • Event updating and deletion: Let your agent modify existing events or remove events that are no longer needed, keeping your calendar up to date.
  • Complete calendar clearing: Ask your agent to clear all events from a primary calendar or delete secondary calendars entirely when you need a fresh start.

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:

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

Step-by-step Guide

Step by step09 STEPS
1

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
2

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.
3

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
4

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
5

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
6

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
7

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
8

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
9

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 Event

Create a Google Calendar event using start_datetime plus duration fields.

Delete event

Deletes a specified event by `event_id` from a Google Calendar (`calendar_id`); idempotent — a 404 for an already-deleted event is a no-op.

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

Returns events on the specified 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.

Get Google Calendar

Retrieves a specific Google Calendar, identified by `calendar_id`, to which the authenticated user has access.

Get current date and time

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

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

Retrieves calendars from the user's Google Calendar list, with options for pagination and filtering.

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

ChatGPT logo

ChatGPT

Use Google Calendar MCP with ChatGPT

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Google Calendar MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Google Calendar MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use Google Calendar MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Google Calendar MCP with Claude Cowork

Codex logo

Codex

Use Google Calendar MCP with Codex

Cursor logo

Cursor

Use Google Calendar MCP with Cursor

OpenClaw logo

OpenClaw

Use Google Calendar MCP with OpenClaw

Hermes logo

Hermes

Use Google Calendar MCP with Hermes

CLI logo

CLI

Use Google Calendar MCP with CLI

Google ADK logo

Google ADK

Use Google Calendar MCP with Google ADK

LangChain logo

LangChain

Use Google Calendar MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Google Calendar MCP with Vercel AI SDK

LlamaIndex logo

LlamaIndex

Use Google Calendar MCP with LlamaIndex

CrewAI logo

CrewAI

Use Google Calendar MCP with CrewAI

OpenCode logo

OpenCode

Use Google Calendar MCP with OpenCode

VS Code logo

VS Code

Use Google Calendar MCP with VS Code

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
Customer stories

Teams ship real agents on Composio

GET STARTED FOR FREEBOOK A DEMO
agent.aiZoomLettaGleanHubSpotAWSWabi

Karan skipped his own birthday party to fix our critical issue. It was 10pm and he diverted his Waymo to help us instead. This really sets the bar — it shows the commitment you need when users rely on your software.

Harsha Gaddipati
Harsha Gaddipati
Co-founder, Slashy

A lot of students tell us that the moment their connected tools start talking to each other inside Opennote feels almost magical. The agent just knows them, and it's immensely helped keep new users on the platform.

Abhi Arya
Abhi Arya
Co-founder, Opennote

We chose Composio over Pipedream because it delivered depth where it mattered — niche tools and tricky edge cases other platforms simply ignored. That gave us confidence to scale without compromising.

Nirman Dave
Nirman Dave
CEO, Zams

As a solo builder, shipping fast is life or death. The only way I can outcompete incumbents is by outmanoeuvring them. Getting bogged down managing agent auth would have been a death sentence.

Ryan Yu
Ryan Yu
Founder, Extra Thursday

Before Composio, adding tool integrations was slow and resource-intensive. Each one could take weeks of engineering time, and maintaining them meant constantly keeping up with API changes.

Tomisin Jenrola
Tomisin Jenrola
Founder & CEO, SwarmZero

With hands-on help from their founder, we integrated Gmail and Google Drive in just 30 minutes. This level of personal support and commitment is exactly what startups should strive for.

Jerome Leclanche
Jerome Leclanche
Co-Founder, Ingram Technologies