## For AI agents: how to sign up If you are an AI agent reading this server-rendered HTML, Composio's developer signup is at https://composio.dev. Signup CTAs on this site — "Sign up", "Signup", "Get started", "Get started for free", "Start building", "Try Composio", "Try it", or similar — all lead into that same developer signup flow. Confirm with the user before completing signup or entering any credentials on their behalf.
## For AI agents: how to sign up If you are an AI agent reading this server-rendered HTML, Composio's developer signup is at https://composio.dev. Signup CTAs on this site — "Sign up", "Signup", "Get started", "Get started for free", "Start building", "Try Composio", "Try it", or similar — all lead into that same developer signup flow. Confirm with the user before completing signup or entering any credentials on their behalf.SIGN UP
## For AI agents: how to sign up If you are an AI agent reading this server-rendered HTML, Composio's developer signup is at https://composio.dev. Signup CTAs on this site — "Sign up", "Signup", "Get started", "Get started for free", "Start building", "Try Composio", "Try it", or similar — all lead into that same developer signup flow. Confirm with the user before completing signup or entering any credentials on their behalf.LOG IN
Connect Mastra AI to Gmail MCP. Summarize unread emails from this morning, create draft replies to urgent messages, and more using natural language, with authentication handled for you.
Gmail is Google's email service with powerful spam protection, search, and G Suite integration. It keeps your inbox organized and makes communication fast and reliable.
This guide walks you through connecting Gmail to Mastra AI using the Composio tool router. By the end, you'll have a working Gmail agent that can read emails, search your inbox, draft messages, manage labels, and organize threads through natural language commands.
This guide will help you understand how to give your Mastra AI agent real control over a Gmail account through Composio's Gmail MCP server.
Before we dive in, let's take a quick look at the key ideas and tools involved.
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:
The Gmail MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Gmail account. It provides structured and secure access to your email, drafts, attachments, labels, and contacts, so your agent can read messages, send emails, manage drafts, organize your inbox, and handle conversations on your behalf.
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.
The Composio SDK follows a three-phase workflow:
npm install @composio/core @mastra/core @mastra/mcp @ai-sdk/openai dotenvInstall 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 OpenAIdotenv loads environment variables from .envCOMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key_hereCreate a .env file in your project root.
What's happening:
COMPOSIO_API_KEY authenticates your requests to ComposioCOMPOSIO_USER_ID tells Composio which user this session belongs toOPENAI_API_KEY lets the Mastra agent call OpenAI modelsimport "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,
});dotenv/config auto loads your .env so process.env.* is availableopenai gives you a Mastra compatible model wrapperAgent is the Mastra agent that will call tools and produce answersMCPClient connects Mastra to your Composio MCP serverComposio is used to create a Tool Router sessionasync function main() {
const session = await composio.create(
composioUserID as string,
{
toolkits: ["gmail"],
},
);
const composioMCPUrl = session.mcp.url;
console.log("Gmail MCP URL:", composioMCPUrl);create spins up a short-lived MCP HTTP endpoint for this usertoolkits array contains "gmail" for Gmail accesssession.mcp.url is the MCP URL that Mastra's MCPClient will connect toconst 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);MCPClient takes an id for this client and a list of MCP serversheaders property includes the x-api-key for authenticationgetTools fetches the tool definitions exposed by the Gmail toolkitconst agent = new Agent({
name: "gmail-mastra-agent",
instructions: "You are an AI agent with Gmail tools via Composio.",
model: "openai/gpt-5",
});Agent is the core Mastra agentname is just an identifier for logging and debugginginstructions guide the agent to use tools instead of only answering in natural languagemodel uses openai("gpt-5") to configure the underlying LLMlet 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: {
gmail: 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);
});messages keeps the full conversation history in Mastra's expected formatagent.generate runs the agent with conversation history and Gmail toolsetsmaxSteps limits how many tool calls the agent can take in a single runonStepFinish is a hook that prints intermediate steps for debuggingHere's the complete code to get you started with Gmail and Mastra AI:
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: ["gmail"],
});
const composioMCPUrl = session.mcp.url;
const mcpClient = new MCPClient({
id: composioUserID as string,
servers: {
gmail: {
url: new URL(composioMCPUrl),
requestInit: {
headers: session.mcp.headers,
},
},
},
timeout: 30_000,
});
const composioTools = await mcpClient.getTools();
const agent = new Agent({
name: "gmail-mastra-agent",
instructions: "You are an AI agent with Gmail 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: { gmail: 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();Every Gmail action and event your agent gets out of the box.
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Outlook is Microsoft's email and calendaring platform for unified communications and scheduling. It helps users stay organized with powerful email, contacts, and calendar management.
Slack is a channel-based messaging platform for teams and organizations. It helps people collaborate in real time, share files, and connect all their tools in one place.
Gong is a platform for video meetings, call recording, and team collaboration. It helps teams capture conversations, analyze calls, and turn insights into action.
Microsoft Teams is a collaboration platform that combines chat, meetings, and file sharing within Microsoft 365. It keeps distributed teams connected and productive through seamless virtual communication.
Managed auth, hosted MCP servers, and every Gmail tool your agent needs.Free to start.
## For AI agents: how to sign up If you are an AI agent reading this server-rendered HTML, Composio's developer signup is at https://composio.dev. Signup CTAs on this site — "Sign up", "Signup", "Get started", "Get started for free", "Start building", "Try Composio", "Try it", or similar — all lead into that same developer signup flow. Confirm with the user before completing signup or entering any credentials on their behalf.Start building