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How to integrate Esignatures io MCP with Mastra AI

Connect Mastra AI to Esignatures io MCP. Send a contract to a new client for signature, list all available contract templates, and more using natural language, with authentication handled for you.

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Esignatures io is an e-signature platform for sending and signing contracts online. Its mobile-friendly experience streamlines contract management and signing workflows.

17 Tools

Introduction

This guide walks you through connecting Esignatures io to Mastra AI using the Composio tool router. By the end, you'll have a working Esignatures io agent that can create and send contracts, manage templates and collaborators, add and update signers, preview contract PDFs, and withdraw contracts through natural language commands.

This guide will help you understand how to give your Mastra AI agent real control over a Esignatures io account through Composio's Esignatures io MCP server.

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

Also integrate Esignatures io with

Claude CodeClaude CoworkOpenAI Agents SDKClaude Agent SDKGrok BotCodexOpenClawHermesAtomic AgentGoogle ADKLangChainVercel AI SDKLlamaIndexCrewAIPydantic AIAutoGen

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 Esignatures io tools
  • Connect Mastra's MCP client to the Composio generated MCP URL
  • Fetch Esignatures io 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 Esignatures io 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 Esignatures io MCP server, and what's possible with it?

The Esignatures io MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Esignatures io account. It provides structured and secure access to your contract management tools, so your agent can create contracts, manage templates, handle signer profiles, and control contract workflows seamlessly on your behalf.

  • Automated contract creation and sending: Instantly generate and send new contracts for signature using pre-built templates and custom signer details.
  • Template management and organization: Allow your agent to create, retrieve, list, and delete contract templates for easy document standardization and reuse.
  • Signer profile creation: Effortlessly add new signers to your account, making it simple to initiate or update signature requests as needed.
  • Contract withdrawal and workflow control: Instantly withdraw contracts that should no longer be signed, preventing further action on outdated or incorrect documents.

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 Esignatures io 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 Esignatures io

typescript
async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["esignatures_io"],
    },
  );

  const composioMCPUrl = session.mcp.url;
  console.log("Esignatures io MCP URL:", composioMCPUrl);
What's happening:
  • create spins up a short-lived MCP HTTP endpoint for this user
  • The toolkits array contains "esignatures_io" for Esignatures io 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 Esignatures io toolkit
8

Create the Mastra agent

typescript
const agent = new Agent({
    name: "esignatures_io-mastra-agent",
    instructions: "You are an AI agent with Esignatures io 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: {
        esignatures_io: 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 Esignatures io 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 Esignatures io 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: ["esignatures_io"],
  });

  const composioMCPUrl = session.mcp.url;

  const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      esignatures_io: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "esignatures_io-mastra-agent",
    instructions: "You are an AI agent with Esignatures io 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: { esignatures_io: 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 Esignatures io 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

Supported Tools

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

Add Template Collaborator

Tool to grant editing access to a template with optional email invitation.

Copy Template

Tool to duplicate an existing template with optional customization.

Create Contract

Tool to create a new contract using a specified template and signer details.

Create Signer

Add a signer to an existing contract using the signer's name and email, with optional details such as company and redirect URL.

Create Template

Tool to create a new template.

Delete Signer

Tool to remove a signer from a contract.

Delete Template

Tool to delete a specific template by its ID.

Generate Contract PDF Preview

Tool to generate a PDF preview of a contract and receive a webhook notification with a download URL.

Get Contract

Retrieve a contract by ID, including its status, signer information, signer-entered values, and signed PDF URL when available.

Get Template

Tool to retrieve details of a specific template by its ID.

List Template Collaborators

Tool to retrieve all collaborators with editing access to a template.

List Templates

Tool to retrieve a list of all templates.

Remove Template Collaborator

Tool to revoke a collaborator's template editing permissions.

Send Contract to Signer

Tool to send or resend a contract signature request to a specific signer via their configured communication channel.

Update Signer

Tool to update contact details of an existing signer on a contract.

Update Template

Tool to update an existing template's content, title, or labels.

Withdraw Contract

Tool to withdraw a contract by its ID.

FRAMEWORKS

How to build Esignatures io MCP Agent with another framework

Claude Code logo

Claude Code

Use Esignatures io MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use Esignatures io MCP with Claude Cowork

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Esignatures io MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Esignatures io MCP with Claude Agent SDK

Grok Bot logo

Grok Bot

Use Esignatures io MCP with Grok Bot

Codex logo

Codex

Use Esignatures io MCP with Codex

OpenClaw logo

OpenClaw

Use Esignatures io MCP with OpenClaw

Hermes logo

Hermes

Use Esignatures io MCP with Hermes

Atomic Agent logo

Atomic Agent

Use Esignatures io MCP with Atomic Agent

Google ADK logo

Google ADK

Use Esignatures io MCP with Google ADK

LangChain logo

LangChain

Use Esignatures io MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Esignatures io MCP with Vercel AI SDK

LlamaIndex logo

LlamaIndex

Use Esignatures io MCP with LlamaIndex

CrewAI logo

CrewAI

Use Esignatures io MCP with CrewAI

Pydantic AI logo

Pydantic AI

Use Esignatures io MCP with Pydantic AI

AutoGen logo

AutoGen

Use Esignatures io MCP with AutoGen

FAQ

Frequently asked questions

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

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

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