How to integrate Gmail MCP with LlamaIndex

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Introduction

This guide walks you through connecting Gmail to LlamaIndex 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 LlamaIndex 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.

Also integrate Gmail with

TL;DR

Here's what you'll learn:
  • Set your OpenAI and Composio API keys
  • Install LlamaIndex and Composio packages
  • Create a Composio Tool Router session for Gmail
  • Connect LlamaIndex to the Gmail MCP server
  • Build a Gmail-powered agent using LlamaIndex
  • Interact with Gmail through natural language

What is LlamaIndex?

LlamaIndex is a data framework for building LLM applications. It provides tools for connecting LLMs to external data sources and services through agents and tools.

Key features include:

  • ReAct Agent: Reasoning and acting pattern for tool-using agents
  • MCP Tools: Native support for Model Context Protocol
  • Context Management: Maintain conversation context across interactions
  • Async Support: Built for async/await patterns

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

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, so your agent can search, read, draft, organize, and even manage contacts in your mailbox—all on your behalf.

  • Advanced email search and retrieval: Effortlessly instruct your agent to fetch emails by sender, subject, label, date, or keywords, and even retrieve full message content or threads.
  • Automated drafting and sending: Have your agent create new email drafts, craft replies, add CC/BCC, include attachments, and handle threading to streamline communication.
  • Smart label and inbox organization: Let the agent create new labels, apply or remove labels from emails, and keep your inbox clutter-free by archiving or moving messages.
  • Contact and thread management: Fetch your Gmail contacts, pull entire conversation threads, or download specific attachments to make follow-ups a breeze.
  • Email and draft cleanup: Direct your agent to permanently delete emails or drafts, helping you maintain a tidy mailbox with minimal effort.

Supported Tools & Triggers

Tools
Triggers
Modify email labelsAdds and/or removes specified Gmail labels for a message; ensure `message_id` and all `label_ids` are valid (use 'listLabels' for custom label IDs).
Batch delete Gmail messagesTool to permanently delete multiple Gmail messages in bulk, bypassing Trash with no recovery possible.
Batch modify Gmail messagesModify labels on multiple Gmail messages in one efficient API call.
Create email draftCreates a Gmail email draft.
Create Gmail filterTool to create a new Gmail filter with specified criteria and actions.
Create labelCreates a new label with a unique name in the specified user's Gmail account.
Create Prompt PostSend a one-shot prompt to the Sanity Content Agent.
Delete DraftPermanently deletes a specific Gmail draft using its ID with no recovery possible; verify the correct `draft_id` and obtain explicit user confirmation before calling.
Delete Gmail filterTool to permanently delete a Gmail filter by its ID.
Delete label from account (permanent)Permanently DELETES a user-created Gmail label from the account (not from a message).
Delete messagePermanently deletes a specific email message by its ID from a Gmail mailbox; for `user_id`, use 'me' for the authenticated user or an email address to which the authenticated user has delegated access.
Delete threadTool to immediately and permanently delete a specified thread and all its messages.
Fetch emailsFetches a list of email messages from a Gmail account, supporting filtering, pagination, and optional full content retrieval.
Fetch message by message IDFetches a specific email message by its ID, provided the `message_id` exists and is accessible to the authenticated `user_id`.
Fetch Message by Thread IDRetrieves messages from a Gmail thread using its `thread_id`, where the thread must be accessible by the specified `user_id`.
Forward email messageForward an existing Gmail message to specified recipients, preserving original body and attachments.
Get Gmail attachmentRetrieves a specific attachment by ID from a message in a user's Gmail mailbox, requiring valid message and attachment IDs.
Get Auto-Forwarding SettingsTool to get the auto-forwarding setting for the specified account.
Get contactsFetches contacts (connections) for the authenticated Google account, allowing selection of specific data fields and pagination.
Get DraftRetrieves a single Gmail draft by its ID.
Get Gmail filterTool to retrieve a specific Gmail filter by its ID.
Get label detailsGets details for a specified Gmail label.
Get Language SettingsTool to retrieve the language settings for a Gmail user.
Get PeopleRetrieves either a specific person's details (using `resource_name`) or lists 'Other Contacts' (if `other_contacts` is true), with `person_fields` specifying the data to return.
Get ProfileRetrieves Gmail profile information (email address, aggregate messagesTotal/threadsTotal, historyId) for a user.
Get Vacation SettingsTool to retrieve vacation responder settings for a Gmail user.
Import messageTool to import a message into the user's mailbox with standard email delivery scanning and classification.
Insert message into mailboxTool to insert a message into the user's mailbox similar to IMAP APPEND.
List CSE identitiesTool to list client-side encrypted identities for an authenticated user.
List CSE key pairsTool to list client-side encryption key pairs for an authenticated user.
List DraftsRetrieves a paginated list of email drafts from a user's Gmail account.
List Gmail filtersTool to list all Gmail filters (rules) in the mailbox.
List forwarding addressesTool to list all forwarding addresses for the specified Gmail account.
List Gmail historyTool to list Gmail mailbox change history since a known startHistoryId.
List Gmail labelsRetrieves all system and user-created labels for a Gmail account in a single unpaginated response.
List send-as aliasesLists the send-as aliases for a Gmail account, including the primary address and custom 'from' aliases.
List S/MIME configsLists S/MIME configs for the specified send-as alias.
List threadsRetrieves a list of email threads from a Gmail account, identified by `user_id` (email address or 'me'), supporting filtering and pagination.
Modify thread labelsAdds or removes specified existing label IDs from a Gmail thread, affecting all its messages; ensure the thread ID is valid.
Trash threadMoves the specified thread to the trash.
Move to TrashMoves an existing, non-deleted email message to the trash for the specified user.
Patch LabelPatches the specified user-created label.
Patch send-as aliasTool to patch the specified send-as alias for a Gmail user.
Reply to email threadSends a reply within a specific Gmail thread using the original thread's subject; do not provide a custom subject as it will start a new conversation instead of replying in-thread.
Search PeopleSearches contacts by matching the query against names, nicknames, emails, phone numbers, and organizations, optionally including 'Other Contacts'.
Send DraftSends an existing draft email AS-IS to recipients already defined within the draft.
Send EmailSends an email via Gmail API using the authenticated user's Google profile display name.
Get IMAP SettingsRetrieves the IMAP settings for a Gmail user account, including whether IMAP is enabled, auto-expunge behavior, expunge behavior, and maximum folder size.
Get POP settingsTool to retrieve POP settings for a Gmail account.
Get send-as aliasTool to retrieve a specific send-as alias configuration for a Gmail user.
Stop watch notificationsTool to stop receiving push notifications for a Gmail mailbox.
Untrash MessageTool to remove a message from trash in Gmail.
Untrash threadTool to remove a thread from trash in Gmail.
Update draftUpdates (replaces) an existing Gmail draft's content in-place by draft ID.
Update IMAP settingsTool to update IMAP settings for a Gmail account.
Update LabelTool to update the properties of an existing Gmail label.
Update Language SettingsTool to update the language settings for a Gmail user.
Update POP settingsTool to update POP settings for a Gmail account.
Update send-as aliasTool to update a send-as alias for a Gmail user.
Update User Attributes ValuesUpdate user attribute values for a resource.
Update Vacation SettingsTool to update vacation responder settings for a Gmail user.

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

Prerequisites

Before you begin, make sure you have:
  • Python 3.8/Node 16 or higher installed
  • A Composio account with the API key
  • An OpenAI API key
  • A Gmail account and project
  • Basic familiarity with async Python/Typescript

Getting API Keys for OpenAI, Composio, and Gmail

OpenAI API key (OPENAI_API_KEY)
  • Go to the OpenAI dashboard
  • Create an API key if you don't have one
  • Assign it to OPENAI_API_KEY in .env
Composio API key and user ID
  • Log into the Composio dashboard
  • Copy your API key from Settings
    • Use this as COMPOSIO_API_KEY
  • Pick a stable user identifier (email or ID)
    • Use this as COMPOSIO_USER_ID

Installing dependencies

pip install composio-llamaindex llama-index llama-index-llms-openai llama-index-tools-mcp python-dotenv

Create a new Python project and install the necessary dependencies:

  • composio-llamaindex: Composio's LlamaIndex integration
  • llama-index: Core LlamaIndex framework
  • llama-index-llms-openai: OpenAI LLM integration
  • llama-index-tools-mcp: MCP client for LlamaIndex
  • python-dotenv: Environment variable management

Set environment variables

bash
OPENAI_API_KEY=your-openai-api-key
COMPOSIO_API_KEY=your-composio-api-key
COMPOSIO_USER_ID=your-user-id

Create a .env file in your project root:

These credentials will be used to:

  • Authenticate with OpenAI's GPT-5 model
  • Connect to Composio's Tool Router
  • Identify your Composio user session for Gmail access

Import modules

import asyncio
import os
import dotenv

from composio import Composio
from composio_llamaindex import LlamaIndexProvider
from llama_index.core.agent.workflow import ReActAgent
from llama_index.core.workflow import Context
from llama_index.llms.openai import OpenAI
from llama_index.tools.mcp import BasicMCPClient, McpToolSpec

dotenv.load_dotenv()

Create a new file called gmail_llamaindex_agent.py and import the required modules:

Key imports:

  • asyncio: For async/await support
  • Composio: Main client for Composio services
  • LlamaIndexProvider: Adapts Composio tools for LlamaIndex
  • ReActAgent: LlamaIndex's reasoning and action agent
  • BasicMCPClient: Connects to MCP endpoints
  • McpToolSpec: Converts MCP tools to LlamaIndex format

Load environment variables and initialize Composio

OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not OPENAI_API_KEY:
    raise ValueError("OPENAI_API_KEY is not set in the environment")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set in the environment")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set in the environment")

What's happening:

This ensures missing credentials cause early, clear errors before the agent attempts to initialise.

Create a Tool Router session and build the agent function

async def build_agent() -> ReActAgent:
    composio_client = Composio(
        api_key=COMPOSIO_API_KEY,
        provider=LlamaIndexProvider(),
    )

    session = composio_client.create(
        user_id=COMPOSIO_USER_ID,
        toolkits=["gmail"],
    )

    mcp_url = session.mcp.url
    print(f"Composio MCP URL: {mcp_url}")

    mcp_client = BasicMCPClient(mcp_url, headers={"x-api-key": COMPOSIO_API_KEY})
    mcp_tool_spec = McpToolSpec(client=mcp_client)
    tools = await mcp_tool_spec.to_tool_list_async()

    llm = OpenAI(model="gpt-5")

    description = "An agent that uses Composio Tool Router MCP tools to perform Gmail actions."
    system_prompt = """
    You are a helpful assistant connected to Composio Tool Router.
    Use the available tools to answer user queries and perform Gmail actions.
    """
    return ReActAgent(tools=tools, llm=llm, description=description, system_prompt=system_prompt, verbose=True)

What's happening here:

  • We create a Composio client using your API key and configure it with the LlamaIndex provider
  • We then create a tool router MCP session for your user, specifying the toolkits we want to use (in this case, gmail)
  • The session returns an MCP HTTP endpoint URL that acts as a gateway to all your configured tools
  • LlamaIndex will connect to this endpoint to dynamically discover and use the available Gmail tools.
  • The MCP tools are mapped to LlamaIndex-compatible tools and plug them into the Agent.

Create an interactive chat loop

async def chat_loop(agent: ReActAgent) -> None:
    ctx = Context(agent)
    print("Type 'quit', 'exit', or Ctrl+C to stop.")

    while True:
        try:
            user_input = input("\nYou: ").strip()
        except (KeyboardInterrupt, EOFError):
            print("\nBye!")
            break

        if not user_input or user_input.lower() in {"quit", "exit"}:
            print("Bye!")
            break

        try:
            print("Agent: ", end="", flush=True)
            handler = agent.run(user_input, ctx=ctx)

            async for event in handler.stream_events():
                # Stream token-by-token from LLM responses
                if hasattr(event, "delta") and event.delta:
                    print(event.delta, end="", flush=True)
                # Show tool calls as they happen
                elif hasattr(event, "tool_name"):
                    print(f"\n[Using tool: {event.tool_name}]", flush=True)

            # Get final response
            response = await handler
            print()  # Newline after streaming
        except KeyboardInterrupt:
            print("\n[Interrupted]")
            continue
        except Exception as e:
            print(f"\nError: {e}")

What's happening here:

  • We're creating a direct terminal interface to chat with your Gmail database
  • The LLM's responses are streamed to the CLI for faster interaction.
  • The agent uses context to maintain conversation history
  • You can type 'quit' or 'exit' to stop the chat loop gracefully
  • Agent responses and any errors are displayed in a clear, readable format

Define the main entry point

async def main() -> None:
    agent = await build_agent()
    await chat_loop(agent)

if __name__ == "__main__":
    # Handle Ctrl+C gracefully
    signal.signal(signal.SIGINT, lambda s, f: (print("\nBye!"), exit(0)))
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        print("\nBye!")

What's happening here:

  • We're orchestrating the entire application flow
  • The agent gets built with proper error handling
  • Then we kick off the interactive chat loop so you can start talking to Gmail

Run the agent

npx ts-node llamaindex-agent.ts

When prompted, authenticate and authorise your agent with Gmail, then start asking questions.

Complete Code

Here's the complete code to get you started with Gmail and LlamaIndex:

import asyncio
import os
import signal
import dotenv

from composio import Composio
from composio_llamaindex import LlamaIndexProvider
from llama_index.core.agent.workflow import ReActAgent
from llama_index.core.workflow import Context
from llama_index.llms.openai import OpenAI
from llama_index.tools.mcp import BasicMCPClient, McpToolSpec

dotenv.load_dotenv()

OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not OPENAI_API_KEY:
    raise ValueError("OPENAI_API_KEY is not set")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set")

async def build_agent() -> ReActAgent:
    composio_client = Composio(
        api_key=COMPOSIO_API_KEY,
        provider=LlamaIndexProvider(),
    )

    session = composio_client.create(
        user_id=COMPOSIO_USER_ID,
        toolkits=["gmail"],
    )

    mcp_url = session.mcp.url
    print(f"Composio MCP URL: {mcp_url}")

    mcp_client = BasicMCPClient(mcp_url, headers={"x-api-key": COMPOSIO_API_KEY})
    mcp_tool_spec = McpToolSpec(client=mcp_client)
    tools = await mcp_tool_spec.to_tool_list_async()

    llm = OpenAI(model="gpt-5")
    description = "An agent that uses Composio Tool Router MCP tools to perform Gmail actions."
    system_prompt = """
    You are a helpful assistant connected to Composio Tool Router.
    Use the available tools to answer user queries and perform Gmail actions.
    """
    return ReActAgent(
        tools=tools,
        llm=llm,
        description=description,
        system_prompt=system_prompt,
        verbose=True,
    );

async def chat_loop(agent: ReActAgent) -> None:
    ctx = Context(agent)
    print("Type 'quit', 'exit', or Ctrl+C to stop.")

    while True:
        try:
            user_input = input("\nYou: ").strip()
        except (KeyboardInterrupt, EOFError):
            print("\nBye!")
            break

        if not user_input or user_input.lower() in {"quit", "exit"}:
            print("Bye!")
            break

        try:
            print("Agent: ", end="", flush=True)
            handler = agent.run(user_input, ctx=ctx)

            async for event in handler.stream_events():
                # Stream token-by-token from LLM responses
                if hasattr(event, "delta") and event.delta:
                    print(event.delta, end="", flush=True)
                # Show tool calls as they happen
                elif hasattr(event, "tool_name"):
                    print(f"\n[Using tool: {event.tool_name}]", flush=True)

            # Get final response
            response = await handler
            print()  # Newline after streaming
        except KeyboardInterrupt:
            print("\n[Interrupted]")
            continue
        except Exception as e:
            print(f"\nError: {e}")

async def main() -> None:
    agent = await build_agent()
    await chat_loop(agent)

if __name__ == "__main__":
    # Handle Ctrl+C gracefully
    signal.signal(signal.SIGINT, lambda s, f: (print("\nBye!"), exit(0)))
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        print("\nBye!")

Conclusion

You've successfully connected Gmail to LlamaIndex through Composio's Tool Router MCP layer. Key takeaways:
  • Tool Router dynamically exposes Gmail tools through an MCP endpoint
  • LlamaIndex's ReActAgent handles reasoning and orchestration; Composio handles integrations
  • The agent becomes more capable without increasing prompt size
  • Async Python provides clean, efficient execution of agent workflows
You can easily extend this to other toolkits like Gmail, Notion, Stripe, GitHub, and more by adding them to the toolkits parameter.

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FAQ

What are the differences in Tool Router MCP and Gmail MCP?

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

Can I use Tool Router MCP with LlamaIndex?

Yes, you can. LlamaIndex 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 Gmail tools.

Can I manage the permissions and scopes for Gmail while using Tool Router?

Yes, absolutely. You can configure which Gmail 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.

How safe is my data with Composio Tool Router?

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 Gmail data and credentials are handled as safely as possible.

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