How to integrate Msg91 MCP with Claude Agent SDK

This guide walks you through connecting Msg91 to the Claude Agent SDK using the Composio tool router. By the end, you'll have a working Msg91 agent that can send sms to new customer leads, list all ongoing marketing campaigns, fetch failed event logs from last week through natural language commands. This guide will help you understand how to give your Claude Agent SDK agent real control over a Msg91 account through Composio's Msg91 MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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MSG91 is a cloud communication platform for sending SMS, WhatsApp, Email, and Voice notifications. It lets businesses securely reach customers across multiple channels from one unified API.

8 Tools

Introduction

This guide walks you through connecting Msg91 to the Claude Agent SDK using the Composio tool router. By the end, you'll have a working Msg91 agent that can send sms to new customer leads, list all ongoing marketing campaigns, fetch failed event logs from last week through natural language commands.

This guide will help you understand how to give your Claude Agent SDK agent real control over a Msg91 account through Composio's Msg91 MCP server.

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

Also integrate Msg91 with

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TL;DR

Here's what you'll learn:
  • Get and set up your Claude/Anthropic and Composio API keys
  • Install the necessary dependencies
  • Initialize Composio and create a Tool Router session for Msg91
  • Configure an AI agent that can use Msg91 as a tool
  • Run a live chat session where you can ask the agent to perform Msg91 operations

What is Claude Agent SDK?

The Claude Agent SDK is Anthropic's official framework for building AI agents powered by Claude. It provides a streamlined interface for creating agents with MCP tool support and conversation management.

Key features include:

  • Native MCP Support: Built-in support for Model Context Protocol servers
  • Permission Modes: Control tool execution permissions
  • Streaming Responses: Real-time response streaming for interactive applications
  • Context Manager: Clean async context management for sessions

What is the Msg91 MCP server, and what's possible with it?

The Msg91 MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Msg91 account. It provides structured and secure access to your SMS, campaign, and user event data, so your agent can perform actions like sending SMS messages, tracking campaigns, recording user events, and monitoring delivery failures on your behalf.

  • Send personalized SMS messages: Let your agent dispatch SMS messages to one or multiple recipients, making customer outreach fast and automated.
  • List and track marketing campaigns: Instantly retrieve an overview of all your ongoing or past campaigns, including support for pagination.
  • Create and log user events: Easily record user actions and behaviors in Msg91 Segmento so you can automate engagement and track interactions.
  • Retrieve available event types: Ask your agent to list all defined event types to keep your analytics and segmentation organized and up to date.
  • Monitor failed events for campaigns: Quickly inspect which events failed validation for any campaign, helping you troubleshoot and optimize your communication workflows.

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:
  • Composio API Key and Claude/Anthropic API Key
  • Primary know-how of Claude Agents SDK
  • A Msg91 account
  • Some knowledge of Python
2

Getting API Keys for Claude/Anthropic and Composio

Claude/Anthropic API Key
  • Go to the Anthropic Console and create an API key. You'll need credits to use the models.
  • Keep the API key safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Navigate to your API settings and generate a new API key.
  • Store this key securely as you'll need it for authentication.
3

Install dependencies

npm install @anthropic-ai/claude-agent-sdk @composio/core dotenv

Install the Composio SDK and the Claude Agents SDK.

What's happening:

  • @composio/core provides Composio integration for Anthropic
  • @anthropic-ai/claude-agent-sdk is the core agent framework
  • dotenv/config loads environment variables
4

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here
ANTHROPIC_API_KEY=your_anthropic_api_key_here

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates with Composio
  • USER_ID identifies the user for session management
  • ANTHROPIC_API_KEY authenticates with Anthropic/Claude
5

Import dependencies

import 'dotenv/config';
import readline from 'node:readline';
import { Composio } from '@composio/core';
import { query, type Options } from "@anthropic-ai/claude-agent-sdk";

dotenv.config();
What's happening:
  • We're importing all necessary libraries including the Claude Agent SDK and Composio
  • The dotenv.config() function loads environment variables from your .env file
  • This setup prepares the foundation for connecting Claude with Msg91 functionality
6

Create a Composio instance and Tool Router session

async function chat() {
  const { COMPOSIO_API_KEY, USER_ID } = process.env;
  if (!COMPOSIO_API_KEY || !USER_ID) {
    throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
  }

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

  // Create Tool Router session for Msg91
  const session = await composio.create(USER_ID, {
    toolkits: ['msg91'],
  });
  const mcpUrl = session?.mcp.url;
What's happening:
  • The function checks for the required COMPOSIO_API_KEY environment variable
  • We're creating a Composio instance using our API key
  • The create method creates a Tool Router session for Msg91
  • The returned url is the MCP server URL that your agent will use
7

Configure Claude Agent with MCP

const options: Options = {
  permissionMode: 'bypassPermissions',
  mcpServers: {
    composio: {
      type: 'http',
      url: mcpUrl,
      headers: { 'x-api-key': COMPOSIO_API_KEY }
    }
  },
  systemPrompt: 'You are a helpful assistant with access to Msg91 tools via Composio.',
  maxTurns: 10,
};
What's happening:
  • We're configuring the Claude Agent options with the MCP server URL
  • permissionMode: 'bypassPermissions' allows the agent to execute operations without asking for permission each time
  • The system prompt instructs the agent that it has access to Msg91
  • maxTurns: 10 limits the conversation length to prevent excessive API usage
8

Create client and start chat loop

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

  console.log('\nChat started. Type "exit" to quit.\n');

  let isProcessing = false;

  async function ask(prompt: string) {
    isProcessing = true;
    rl.pause();

    process.stdout.write('Claude is thinking...');
    const stream = query({ prompt, options });

    let firstChunk = true;
    for await (const msg of stream) {
      const content = (msg as any).message?.content || (msg as any).content;
      if (Array.isArray(content)) {
        for (const block of content) {
          if (block.type === 'text' && block.text) {
            if (firstChunk) {
              process.stdout.write('\r\x1b[K');
              process.stdout.write('Claude: ');
              firstChunk = false;
            }
            process.stdout.write(block.text);
          }
        }
      }
    }
    process.stdout.write('\n\n');

    isProcessing = false;
    rl.resume();
    rl.prompt();
  }

  rl.on('line', async (line) => {
    if (isProcessing) return;

    const input = line.trim();
    if (input === 'exit') {
      rl.close();
      process.exit(0);
    }
    if (input) await ask(input);
    else rl.prompt();
  });

  await ask('What can you help me with?');
}
What's happening:
  • The readline interface is created to handle user input and output
  • The query function is used to send the user's input to the agent
  • The chat loop continues until the user types 'exit' or 'quit'
9

Run the application

try {
  await chat();
} catch (error) {
  console.error(error);
  process.exit(1);
}
What's happening:
  • The chat function is the entry point for the application
  • The try-catch block is used to handle any errors that occur

Complete Code

Here's the complete code to get you started with Msg91 and Claude Agent SDK:

import 'dotenv/config';
import readline from 'node:readline';
import { Composio } from '@composio/core';
import { query, type Options } from "@anthropic-ai/claude-agent-sdk";

async function chat() {
  const { COMPOSIO_API_KEY, USER_ID } = process.env;
  if (!COMPOSIO_API_KEY || !USER_ID) {
    throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
  }

  const composio = new Composio({ apiKey: COMPOSIO_API_KEY });
  const session = await composio.create(USER_ID, {
    toolkits: ['msg91']
  });
  const mcp_url = session?.mcp.url;

  const options: Options = {
    permissionMode: 'bypassPermissions',
    mcpServers: {
      composio: {
        type: 'http',
        url: mcp_url,
        headers: { 'x-api-key': COMPOSIO_API_KEY }
      }
    },
    systemPrompt: 'You are a helpful assistant with access to Msg91 tools via Composio.',
    maxTurns: 10,
  };

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

  console.log('\nChat started. Type "exit" to quit.\n');

  let isProcessing = false;

  async function ask(prompt: string) {
    isProcessing = true;
    rl.pause();

    process.stdout.write('Claude is thinking...');
    const stream = query({ prompt, options });

    let firstChunk = true;
    for await (const msg of stream) {
      const content = (msg as any).message?.content || (msg as any).content;
      if (Array.isArray(content)) {
        for (const block of content) {
          if (block.type === 'text' && block.text) {
            if (firstChunk) {
              process.stdout.write('\r\x1b[K');
              process.stdout.write('Claude: ');
              firstChunk = false;
            }
            process.stdout.write(block.text);
          }
        }
      }
    }
    process.stdout.write('\n\n');

    isProcessing = false;
    rl.resume();
    rl.prompt();
  }

  rl.on('line', async (line) => {
    if (isProcessing) return;

    const input = line.trim();
    if (input === 'exit') {
      rl.close();
      process.exit(0);
    }
    if (input) await ask(input);
    else rl.prompt();
  });

  await ask('What can you help me with?');
}

try {
  await chat();
} catch (error) {
  console.error(error);
  process.exit(1);
}

Conclusion

You've successfully built a Claude Agent SDK agent that can interact with Msg91 through Composio's Tool Router.

Key features:

  • Native MCP support through Claude's agent framework
  • Streaming responses for real-time interaction
  • Permission bypass for smooth automated workflows
You can extend this by adding more toolkits, implementing custom business logic, or building a web interface around the agent.
TOOLS

Supported Tools

Every Msg91 action and event your agent gets out of the box.

Create User Events

Create and track user events in MSG91 Segmento for customer behavior analysis and segmentation.

Get Event Types

Retrieves all event types configured in MSG91 Segmento.

Get Failed Events

Retrieve failed user events from a MSG91 Segmento campaign.

List Campaigns

Tool to list all campaigns in Segmento.

Resend OTP

Resend OTP to the same mobile number via text message or voice call.

Send OTP

Tool to send OTP (One-Time Password) to a mobile number using a pre-configured MSG91 template.

Send SMS via Flow (V5)

Send SMS messages using pre-defined templates via MSG91 Flow API v5.

Verify OTP

Tool to verify an OTP (One-Time Password) sent to a mobile number.

FRAMEWORKS

How to build Msg91 MCP Agent with another framework

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OpenAI Agents SDK

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Claude Code logo

Claude Code

Use Msg91 MCP with Claude Code

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Claude Cowork

Use Msg91 MCP with Claude Cowork

Codex logo

Codex

Use Msg91 MCP with Codex

OpenClaw logo

OpenClaw

Use Msg91 MCP with OpenClaw

Hermes logo

Hermes

Use Msg91 MCP with Hermes

CLI logo

CLI

Use Msg91 MCP with CLI

Google ADK logo

Google ADK

Use Msg91 MCP with Google ADK

LangChain logo

LangChain

Use Msg91 MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Msg91 MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Msg91 MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Msg91 MCP with LlamaIndex

CrewAI logo

CrewAI

Use Msg91 MCP with CrewAI

FAQ

Frequently asked questions

With a standalone Msg91 MCP server, the agents and LLMs can only access a fixed set of Msg91 tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Msg91 and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. Claude Agent SDK 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 Msg91 tools.

Yes, absolutely. You can configure which Msg91 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 Msg91 data and credentials are handled as safely as possible.

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