# How to integrate Resend MCP with LlamaIndex

```json
{
  "title": "How to integrate Resend MCP with LlamaIndex",
  "toolkit": "Resend",
  "toolkit_slug": "resend",
  "framework": "LlamaIndex",
  "framework_slug": "llama-index",
  "url": "https://composio.dev/toolkits/resend/framework/llama-index",
  "markdown_url": "https://composio.dev/toolkits/resend/framework/llama-index.md",
  "updated_at": "2026-05-12T10:23:58.563Z"
}
```

## Introduction

This guide walks you through connecting Resend to LlamaIndex using the Composio tool router. By the end, you'll have a working Resend agent that can create a new contact for your newsletter, list all domains connected to your account, cancel a scheduled marketing email through natural language commands.
This guide will help you understand how to give your LlamaIndex agent real control over a Resend account through Composio's Resend MCP server.
Before we dive in, let's take a quick look at the key ideas and tools involved.

## Also integrate Resend with

- [OpenAI Agents SDK](https://composio.dev/toolkits/resend/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/resend/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/resend/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/resend/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/resend/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/resend/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/resend/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/resend/framework/cli)
- [Google ADK](https://composio.dev/toolkits/resend/framework/google-adk)
- [LangChain](https://composio.dev/toolkits/resend/framework/langchain)
- [Vercel AI SDK](https://composio.dev/toolkits/resend/framework/ai-sdk)
- [Mastra AI](https://composio.dev/toolkits/resend/framework/mastra-ai)
- [CrewAI](https://composio.dev/toolkits/resend/framework/crew-ai)

## 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 Resend
- Connect LlamaIndex to the Resend MCP server
- Build a Resend-powered agent using LlamaIndex
- Interact with Resend 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 Resend MCP server, and what's possible with it?

The Resend MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Resend account. It provides structured and secure access to your email sending and contact management capabilities, so your agent can perform actions like sending emails, managing audiences, creating domains, and handling contacts on your behalf.
- Automated email delivery and scheduling: Ask your agent to send emails instantly or schedule them for later, and even cancel scheduled messages if needed.
- Audience and contact management: Let your agent create, list, or delete audiences and individual contacts, keeping your recipient lists organized without manual effort.
- Domain administration: Easily have your agent set up, list, or remove email sending domains, streamlining onboarding or maintenance for your email infrastructure.
- Seamless recipient segmentation: Direct your agent to group contacts into audiences for targeted campaigns or communications, improving personalization and reach.
- Bulk operations and cleanups: Enable your agent to quickly list, update, or delete multiple contacts, audiences, or domains to maintain a tidy and up-to-date email system.

## Supported Tools

| Tool slug | Name | Description |
|---|---|---|
| `RESEND_ADD_CONTACT_TO_SEGMENT` | Add Contact To Segment | Add an existing contact to a segment in Resend. Use when you need to organize contacts into specific segments for targeted communication. |
| `RESEND_CANCEL_EMAIL` | Cancel Email | Cancel a scheduled email. |
| `RESEND_CREATE_API_KEY` | Create API Key | Create a new API key to authenticate communications with Resend. Use when you need to generate a new authentication token for API access. |
| `RESEND_CREATE_AUDIENCE` | Create Audience | Create a list of contacts. |
| `RESEND_CREATE_CONTACT` | Create Contact | Create a contact in Resend. |
| `RESEND_CREATE_CONTACT_PROPERTY` | Create Contact Property | Tool to create a new contact property in Resend. Use when you need to define custom fields for contacts. |
| `RESEND_CREATE_CONTACT_V2` | Create Contact V2 | Tool to create a new contact in Resend. Use when you need to add a contact to Resend without specifying an audience. |
| `RESEND_CREATE_DOMAIN` | Create Domain | Create a domain through the Resend Email API. The domain is created in a pending/unverified state and cannot be used for sending emails until DNS verification is completed. |
| `RESEND_CREATE_TEMPLATE` | Create Template | Tool to create a new email template in Resend. Use when you need to define reusable email templates with optional variables. |
| `RESEND_CREATE_TOPIC` | Create Topic | Tool to create a new topic to segment your audience. Use when you need to create a topic for organizing contacts by interests or preferences. |
| `RESEND_CREATE_WEBHOOK` | Create Webhook | Tool to create a webhook to receive real-time notifications about email events. Use when you need to set up automated notifications for email status changes. |
| `RESEND_DELETE_API_KEY` | Delete API Key | Remove an existing API key from Resend. Use when you need to revoke or delete an API key. |
| `RESEND_DELETE_AUDIENCE` | Delete Audience | Remove an existing audience. |
| `RESEND_DELETE_CONTACT` | Delete Contact | Delete a contact in Resend. |
| `RESEND_DELETE_CONTACT_BY_ID` | Delete Contact By ID | Tool to remove an existing contact by its ID. Use when you need to delete a contact directly without specifying an audience. |
| `RESEND_DELETE_CONTACT_PROPERTY` | Delete Contact Property | Remove an existing contact property from Resend. |
| `RESEND_DELETE_DOMAIN` | Delete Domain | Delete a domain through the Resend Email API. Deletion is irreversible; ensure no active email traffic or DNS configurations depend on the domain before calling. |
| `RESEND_DELETE_SEGMENT` | Delete Segment | Remove an existing segment. Use when you need to permanently delete a segment by its ID. |
| `RESEND_DELETE_TEMPLATE` | Delete Template | Remove an existing template. Use this action when you need to delete a template from Resend. |
| `RESEND_DELETE_TOPIC` | Delete Topic | Tool to remove an existing topic in Resend. Use when you need to delete a topic. |
| `RESEND_DELETE_WEBHOOK` | Delete Webhook | Remove an existing webhook. Use this to delete a webhook configuration when you no longer need to receive event notifications at that endpoint. |
| `RESEND_DUPLICATE_TEMPLATE` | Duplicate Template | Duplicate an existing template through the Resend Email API. Use when you need to create a copy of an existing template. |
| `RESEND_GET_CONTACT` | Get Contact | Tool to retrieve a single contact from Resend by ID or email. Use when you need to get details of a specific contact using the global contacts endpoint. |
| `RESEND_GET_CONTACT_PROPERTY` | Get Contact Property | Tool to retrieve a single contact property from Resend. Use when you need to get details about a specific contact property by its ID. |
| `RESEND_GET_EMAIL_ATTACHMENT` | Get Email Attachment | Retrieve a single attachment from a sent email. Use when you need to access attachment metadata and download URL. |
| `RESEND_GET_SEGMENT` | Get Segment | Retrieve a single segment by its ID. Use when you need to get detailed information about a specific segment. |
| `RESEND_GET_TEMPLATE` | Get Template | Retrieve a single template by ID or alias from Resend. Use when you need to view template details. |
| `RESEND_GET_TOPIC` | Get Topic | Tool to retrieve a single topic by its ID in Resend. Use when you need to fetch details of a specific topic. |
| `RESEND_GET_WEBHOOK` | Get Webhook | Retrieve a single webhook for the authenticated user. Use this to get details about a specific webhook configuration including its endpoint, subscribed events, and signing secret. |
| `RESEND_LIST_ALL_CONTACTS` | List All Contacts | Tool to retrieve a list of all contacts from Resend. Use when you need to fetch contacts across all audiences with optional pagination. |
| `RESEND_LIST_API_KEYS` | List API Keys | Tool to retrieve a list of API keys for the authenticated user. Use when you need to view all API keys associated with the account, including pagination support for large result sets. |
| `RESEND_LIST_AUDIENCES` | List Audiences | List all audiences. |
| `RESEND_LIST_BROADCASTS` | List Broadcasts | Tool to retrieve a list of broadcasts. Use when you need to fetch all broadcasts or paginate through them. |
| `RESEND_LIST_CONTACT_PROPERTIES` | List Contact Properties | Tool to retrieve a list of contact properties from Resend. Use when you need to view available contact property definitions. |
| `RESEND_LIST_CONTACTS` | List Contacts | List contacts in Resend. |
| `RESEND_LIST_CONTACT_SEGMENTS` | List Contact Segments | Retrieve a list of segments that a contact is part of. Use when you need to determine which segments a specific contact belongs to. |
| `RESEND_LIST_CONTACT_TOPICS` | List Contact Topics | Retrieve a list of topic subscriptions for a contact in Resend. Use when you need to check which topics a specific contact is subscribed to. |
| `RESEND_LIST_DOMAINS` | List Domains | List all domains. Use the returned domain IDs as inputs for tools like RESEND_VERIFY_DOMAIN that require a domain_id. |
| `RESEND_LIST_EMAIL_ATTACHMENTS` | List Email Attachments | Tool to retrieve a list of attachments from a sent email. Use when you need to get information about files attached to an email sent via Resend. |
| `RESEND_LIST_EMAILS` | List Emails | Tool to retrieve a list of emails sent by your team. Use when you need to fetch outbound emails from your account. Supports pagination with limit, after, and before parameters. |
| `RESEND_LIST_RECEIVED_EMAILS` | List Received Emails | Tool to retrieve a list of received emails for the authenticated user. Use when you need to fetch incoming emails from the receiving endpoint. |
| `RESEND_LIST_SEGMENTS` | List Segments | Tool to retrieve a list of segments from Resend. Use when you need to view all available segments for audience management. |
| `RESEND_LIST_TEMPLATES` | List Templates | Tool to retrieve a list of templates from Resend. Use when you need to get all available templates with optional pagination support. |
| `RESEND_LIST_TOPICS` | List Topics | Tool to retrieve a list of topics for the authenticated user. Use when you need to fetch available topics with optional pagination support. |
| `RESEND_LIST_WEBHOOKS` | List Webhooks | Retrieve a list of webhooks for the authenticated user. Use this to view all configured webhooks with their endpoints, event types, and status. |
| `RESEND_PUBLISH_TEMPLATE` | Publish Template | Publish a template through the Resend Email API. Use when you need to make a template publicly available. |
| `RESEND_REMOVE_CONTACT_FROM_SEGMENT` | Remove Contact From Segment | Remove an existing contact from a segment. Use when you need to disassociate a contact from a specific segment. |
| `RESEND_RETRIEVE_AUDIENCE` | Retrieve Audience | Retrieve a single audience. |
| `RESEND_RETRIEVE_CONTACT` | Retrieve Contact | Retrieve a contact in Resend. |
| `RESEND_RETRIEVE_DOMAIN` | Retrieve Domain | Retrieve a single domain. |
| `RESEND_RETRIEVE_EMAIL` | Retrieve Email | Retrieve a single email. |
| `RESEND_SEND_BATCH_EMAILS` | Send Batch Emails | Trigger up to 100 batch emails at once. Use when you need to send multiple emails in a single API request. |
| `RESEND_SEND_EMAIL` | Send Email | Send an email using Resend. Confirm recipients and content with the user before invoking — sends are irreversible. All recipients must be listed explicitly via `to`, `cc`, or `bcc`; audience-based sending is unsupported. Render HTML or plain text externally before passing via `html` or `text`. |
| `RESEND_UPDATE_BROADCAST` | Update Broadcast | Update an existing broadcast in Resend. Use when you need to modify broadcast details like name, subject, content, or recipients. |
| `RESEND_UPDATE_CONTACT` | Update Contact | Tool to update an existing contact in Resend by ID or email. Use when you need to modify contact details such as name or subscription status. |
| `RESEND_UPDATE_CONTACT_PROPERTY` | Update Contact Property | Update an existing contact property in Resend. Only the fallback_value can be updated; the key and type fields cannot be changed after creation. |
| `RESEND_UPDATE_DOMAIN` | Update Domain | Update an existing domain. |
| `RESEND_UPDATE_EMAIL` | Update Email | Update a scheduled email. |
| `RESEND_UPDATE_TEMPLATE` | Update Template | Tool to update an existing email template in Resend. Use when you need to modify template properties such as name, subject, HTML content, or variables. |
| `RESEND_UPDATE_TOPIC` | Update Topic | Tool to update an existing topic in Resend. Use when you need to modify the name of a topic. |
| `RESEND_UPDATE_WEBHOOK` | Update Webhook | Tool to update an existing webhook configuration. Use when you need to modify the endpoint URL, change event subscriptions, or enable/disable a webhook. |
| `RESEND_VERIFY_DOMAIN` | Verify Domain | Verify a domain through the Resend Email API. DNS records must fully propagate before verification succeeds; avoid immediate retries after DNS setup. |

## Supported Triggers

None listed.

## Creating MCP Server - Stand-alone vs Composio SDK

The Resend MCP server is an implementation of the Model Context Protocol that connects your AI agent to Resend. It provides structured and secure access so your agent can perform Resend operations on your behalf through a secure, permission-based interface.
With Composio's managed implementation, you don't have to create your own developer app. For production, if you're building an end product, we recommend using your own credentials. The managed server helps you prototype fast and go from 0-1 faster.

## Step-by-step Guide

### 1. 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 Resend account and project
- Basic familiarity with async Python/Typescript

### 1. Getting API Keys for OpenAI, Composio, and Resend

No description provided.

### 2. Installing dependencies

No description provided.
```python
pip install composio-llamaindex llama-index llama-index-llms-openai llama-index-tools-mcp python-dotenv
```

```typescript
npm install @composio/llamaindex @llamaindex/openai @llamaindex/tools @llamaindex/workflow dotenv
```

### 3. Set environment variables

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

### 4. Import modules

No description provided.
```python
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()
```

```typescript
import "dotenv/config";
import readline from "node:readline/promises";
import { stdin as input, stdout as output } from "node:process";

import { Composio } from "@composio/core";

import { mcp } from "@llamaindex/tools";
import { agent as createAgent } from "@llamaindex/workflow";
import { openai } from "@llamaindex/openai";

dotenv.config();
```

### 5. Load environment variables and initialize Composio

No description provided.
```python
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")
```

```typescript
const OPENAI_API_KEY = process.env.OPENAI_API_KEY;
const COMPOSIO_API_KEY = process.env.COMPOSIO_API_KEY;
const COMPOSIO_USER_ID = process.env.COMPOSIO_USER_ID;

if (!OPENAI_API_KEY) throw new Error("OPENAI_API_KEY is not set");
if (!COMPOSIO_API_KEY) throw new Error("COMPOSIO_API_KEY is not set");
if (!COMPOSIO_USER_ID) throw new Error("COMPOSIO_USER_ID is not set");
```

### 6. Create a Tool Router session and build the agent function

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, resend)
- 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 Resend tools.
- The MCP tools are mapped to LlamaIndex-compatible tools and plug them into the Agent.
```python
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=["resend"],
    )

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

```typescript
async function buildAgent() {

  console.log(`Initializing Composio client...${COMPOSIO_USER_ID!}...`);
  console.log(`COMPOSIO_USER_ID: ${COMPOSIO_USER_ID!}...`);

  const composio = new Composio({
    apiKey: COMPOSIO_API_KEY,
    provider: new LlamaindexProvider(),
  });

  const session = await composio.create(
    COMPOSIO_USER_ID!,
    {
      toolkits: ["resend"],
    },
  );

  const mcpUrl = session.mcp.url;
  console.log(`Composio Tool Router MCP URL: ${mcpUrl}`);

  const server = mcp({
    url: mcpUrl,
    clientName: "composio_tool_router_with_llamaindex",
    requestInit: {
      headers: {
        "x-api-key": COMPOSIO_API_KEY!,
      },
    },
    // verbose: true,
  });

  const tools = await server.tools();

  const llm = openai({ apiKey: OPENAI_API_KEY, model: "gpt-5" });

  const agent = createAgent({
    name: "composio_tool_router_with_llamaindex",
        description : "An agent that uses Composio Tool Router MCP tools to perform actions.",
    systemPrompt:
      "You are a helpful assistant connected to Composio Tool Router."+
"Use the available tools to answer user queries and perform Resend actions." ,
    llm,
    tools,
  });

  return agent;
}
```

### 7. Create an interactive chat loop

No description provided.
```python
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}")
```

```typescript
async function chatLoop(agent: ReturnType<typeof createAgent>) {
  const rl = readline.createInterface({ input, output });

  console.log("Type 'quit' or 'exit' to stop.");

  while (true) {
    let userInput: string;

    try {
      userInput = (await rl.question("\nYou: ")).trim();
    } catch {
      console.log("\nAgent: Bye!");
      break;
    }

    if (!userInput) {
      continue;
    }

    const lower = userInput.toLowerCase();
    if (lower === "quit" || lower === "exit") {
      console.log("Agent: Bye!");
      break;
    }

    try {
      process.stdout.write("Agent: ");

      const stream = agent.runStream(userInput);
      let finalResult: any = null;

      for await (const event of stream) {
        // The event.data contains the streamed content
        const data: any = event.data;

        // Check for streaming delta content
        if (data?.delta) {
          process.stdout.write(data.delta);
        }

        // Store final result for fallback
        if (data?.result || data?.message) {
          finalResult = data;
        }
      }

      // If no streaming happened, show the final result
      if (finalResult) {
        const answer =
          finalResult.result ??
          finalResult.message?.content ??
          finalResult.message ??
          "";
        if (answer && typeof answer === "string" && !answer.includes("[object")) {
          process.stdout.write(answer);
        }
      }

      console.log(); // New line after streaming completes
    } catch (err: any) {
      console.error("\nAgent error:", err?.message ?? err);
    }
  }

  rl.close();
}
```

### 8. Define the main entry point

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 Resend
```python
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!")
```

```typescript
async function main() {
  try {
    const agent = await buildAgent();
    await chatLoop(agent);
  } catch (err) {
    console.error("Failed to start agent:", err);
    process.exit(1);
  }
}

main();
```

### 9. Run the agent

When prompted, authenticate and authorise your agent with Resend, then start asking questions.
```bash
python llamaindex_agent.py
```

```typescript
npx ts-node llamaindex-agent.ts
```

## Complete Code

```python
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=["resend"],
    )

    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 Resend actions."
    system_prompt = """
    You are a helpful assistant connected to Composio Tool Router.
    Use the available tools to answer user queries and perform Resend 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!")
```

```typescript
import "dotenv/config";
import readline from "node:readline/promises";
import { stdin as input, stdout as output } from "node:process";

import { Composio } from "@composio/core";
import { LlamaindexProvider } from "@composio/llamaindex";

import { mcp } from "@llamaindex/tools";
import { agent as createAgent } from "@llamaindex/workflow";
import { openai } from "@llamaindex/openai";

dotenv.config();

const OPENAI_API_KEY = process.env.OPENAI_API_KEY;
const COMPOSIO_API_KEY = process.env.COMPOSIO_API_KEY;
const COMPOSIO_USER_ID = process.env.COMPOSIO_USER_ID;

if (!OPENAI_API_KEY) {
    throw new Error("OPENAI_API_KEY is not set in the environment");
  }
if (!COMPOSIO_API_KEY) {
    throw new Error("COMPOSIO_API_KEY is not set in the environment");
  }
if (!COMPOSIO_USER_ID) {
    throw new Error("COMPOSIO_USER_ID is not set in the environment");
  }

async function buildAgent() {

  console.log(`Initializing Composio client...${COMPOSIO_USER_ID!}...`);
  console.log(`COMPOSIO_USER_ID: ${COMPOSIO_USER_ID!}...`);

  const composio = new Composio({
    apiKey: COMPOSIO_API_KEY,
    provider: new LlamaindexProvider(),
  });

  const session = await composio.create(
    COMPOSIO_USER_ID!,
    {
      toolkits: ["resend"],
    },
  );

  const mcpUrl = session.mcp.url;
  console.log(`Composio Tool Router MCP URL: ${mcpUrl}`);

  const server = mcp({
    url: mcpUrl,
    clientName: "composio_tool_router_with_llamaindex",
    requestInit: {
      headers: {
        "x-api-key": COMPOSIO_API_KEY!,
      },
    },
    // verbose: true,
  });

  const tools = await server.tools();

  const llm = openai({ apiKey: OPENAI_API_KEY, model: "gpt-5" });

  const agent = createAgent({
    name: "composio_tool_router_with_llamaindex",
    description:
      "An agent that uses Composio Tool Router MCP tools to perform actions.",
    systemPrompt:
      "You are a helpful assistant connected to Composio Tool Router."+
"Use the available tools to answer user queries and perform Resend actions." ,
    llm,
    tools,
  });

  return agent;
}

async function chatLoop(agent: ReturnType<typeof createAgent>) {
  const rl = readline.createInterface({ input, output });

  console.log("Type 'quit' or 'exit' to stop.");

  while (true) {
    let userInput: string;

    try {
      userInput = (await rl.question("\nYou: ")).trim();
    } catch {
      console.log("\nAgent: Bye!");
      break;
    }

    if (!userInput) {
      continue;
    }

    const lower = userInput.toLowerCase();
    if (lower === "quit" || lower === "exit") {
      console.log("Agent: Bye!");
      break;
    }

    try {
      process.stdout.write("Agent: ");

      const stream = agent.runStream(userInput);
      let finalResult: any = null;

      for await (const event of stream) {
        // The event.data contains the streamed content
        const data: any = event.data;

        // Check for streaming delta content
        if (data?.delta) {
          process.stdout.write(data.delta);
        }

        // Store final result for fallback
        if (data?.result || data?.message) {
          finalResult = data;
        }
      }

      // If no streaming happened, show the final result
      if (finalResult) {
        const answer =
          finalResult.result ??
          finalResult.message?.content ??
          finalResult.message ??
          "";
        if (answer && typeof answer === "string" && !answer.includes("[object")) {
          process.stdout.write(answer);
        }
      }

      console.log(); // New line after streaming completes
    } catch (err: any) {
      console.error("\nAgent error:", err?.message ?? err);
    }
  }

  rl.close();
}

async function main() {
  try {
    const agent = await buildAgent();
    await chatLoop(agent);
  } catch (err: any) {
    console.error("Failed to start agent:", err?.message ?? err);
    process.exit(1);
  }
}

main();
```

## Conclusion

You've successfully connected Resend to LlamaIndex through Composio's Tool Router MCP layer.
Key takeaways:
- Tool Router dynamically exposes Resend 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.

## How to build Resend MCP Agent with another framework

- [OpenAI Agents SDK](https://composio.dev/toolkits/resend/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/resend/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/resend/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/resend/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/resend/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/resend/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/resend/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/resend/framework/cli)
- [Google ADK](https://composio.dev/toolkits/resend/framework/google-adk)
- [LangChain](https://composio.dev/toolkits/resend/framework/langchain)
- [Vercel AI SDK](https://composio.dev/toolkits/resend/framework/ai-sdk)
- [Mastra AI](https://composio.dev/toolkits/resend/framework/mastra-ai)
- [CrewAI](https://composio.dev/toolkits/resend/framework/crew-ai)

## Related Toolkits

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- [Facebook](https://composio.dev/toolkits/facebook) - Facebook is a social media and advertising platform for businesses and creators. It helps you connect, share, and manage content across your public Facebook Pages.
- [Linkedin](https://composio.dev/toolkits/linkedin) - LinkedIn is a professional networking platform for connecting, sharing content, and engaging with business opportunities. It's the go-to place for building your professional brand and unlocking new career connections.
- [Active campaign](https://composio.dev/toolkits/active_campaign) - ActiveCampaign is a marketing automation and CRM platform for managing email campaigns, sales pipelines, and customer segmentation. It helps businesses engage customers and drive growth through smart automation and targeted outreach.
- [ActiveTrail](https://composio.dev/toolkits/active_trail) - ActiveTrail is a user-friendly email marketing and automation platform. It helps you reach subscribers and automate campaigns with ease.
- [Ahrefs](https://composio.dev/toolkits/ahrefs) - Ahrefs is an SEO and marketing platform for site audits, keyword research, and competitor insights. It helps you improve search rankings and drive organic traffic.
- [Amcards](https://composio.dev/toolkits/amcards) - AMCards lets you create and mail personalized greeting cards online. Build stronger customer relationships with easy, automated card campaigns.
- [Beamer](https://composio.dev/toolkits/beamer) - Beamer is a news and changelog platform for in-app announcements and feature updates. It helps companies boost user engagement by sharing news where users are most active.
- [Benchmark email](https://composio.dev/toolkits/benchmark_email) - Benchmark Email is a platform for creating, sending, and tracking email campaigns. It's built to help you engage audiences and analyze results—all in one place.
- [Bigmailer](https://composio.dev/toolkits/bigmailer) - BigMailer is an email marketing platform for managing multiple brands with white-labeling and automation. It helps teams streamline campaigns and simplify integration with Amazon SES.
- [Brandfetch](https://composio.dev/toolkits/brandfetch) - Brandfetch is an API that delivers company logos, colors, and visual branding assets. It helps marketers and developers keep brand visuals consistent everywhere.
- [Brevo](https://composio.dev/toolkits/brevo) - Brevo is an all-in-one email and SMS marketing platform for transactional messaging, automation, and CRM. It helps businesses engage customers and streamline communications through powerful campaign tools.
- [Campayn](https://composio.dev/toolkits/campayn) - Campayn is an email marketing platform for creating, sending, and managing campaigns. It helps businesses engage contacts and grow audiences with easy-to-use tools.
- [Cardly](https://composio.dev/toolkits/cardly) - Cardly is a platform for creating and sending personalized direct mail to customers. It helps businesses break through the digital clutter by getting real engagement via physical mailboxes.
- [ClickSend](https://composio.dev/toolkits/clicksend) - ClickSend is a cloud-based SMS and email marketing platform for businesses. It streamlines communication by enabling quick message delivery and contact management.
- [Crustdata](https://composio.dev/toolkits/crustdata) - CrustData is an AI-powered data intelligence platform for real-time company and people data. It helps B2B sales teams, AI SDRs, and investors react to live business signals.
- [Curated](https://composio.dev/toolkits/curated) - Curated is a platform for collecting, curating, and publishing newsletters. It streamlines content aggregation and distribution for creators and teams.
- [Customerio](https://composio.dev/toolkits/customerio) - Customer.io is a customer engagement platform for targeted messaging across email, SMS, and push. Easily automate, segment, and track communications with your audience.
- [Cutt ly](https://composio.dev/toolkits/cutt_ly) - Cutt.ly is a URL shortening service for managing and analyzing links. Streamline your workflows with quick, trackable, and branded short URLs.
- [Demio](https://composio.dev/toolkits/demio) - Demio is webinar software built for marketers, offering both live and automated sessions with interactive features. It helps teams engage audiences and optimize lead generation through detailed analytics.

## Frequently Asked Questions

### What are the differences in Tool Router MCP and Resend MCP?

With a standalone Resend MCP server, the agents and LLMs can only access a fixed set of Resend tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Resend 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 Resend tools.

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

Yes, absolutely. You can configure which Resend 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 Resend data and credentials are handled as safely as possible.

---
[See all toolkits](https://composio.dev/toolkits) · [Composio docs](https://docs.composio.dev/llms.txt)