How to integrate eSignatures MCP with Pydantic AI

This guide walks you through connecting eSignatures to Pydantic AI using the Composio tool router. By the end, you'll have a working eSignatures agent that can draft contracts, send contracts for signing, add signers, manage templates, and check contract details through natural language commands. This guide will help you understand how to give your Pydantic AI agent real control over a eSignatures account through Composio's eSignatures MCP server. Before we dive in, let's take a quick look at the key ideas and tools involved.

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eSignatures is an electronic signature platform for creating templates, sending contracts, and managing signers. It helps teams close agreements faster with trackable, paperless signing workflows.

28 Tools

Introduction

This guide walks you through connecting eSignatures to Pydantic AI using the Composio tool router. By the end, you'll have a working eSignatures agent that can draft contracts, send contracts for signing, add signers, manage templates, and check contract details through natural language commands.

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

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

Also integrate eSignatures with

OpenAI Agents SDKClaude Agent SDKClaude CodeClaude CoworkCodexOpenClawHermesCLIGoogle ADKLangChainVercel AI SDKMastra AILlamaIndexCrewAI

TL;DR

Here's what you'll learn:
  • How to set up your Composio API key and User ID
  • How to create a Composio Tool Router session for eSignatures
  • How to attach an MCP Server to a Pydantic AI agent
  • How to stream responses and maintain chat history
  • How to build a simple REPL-style chat interface to test your eSignatures workflows

What is Pydantic AI?

Pydantic AI is a Python framework for building AI agents with strong typing and validation. It leverages Pydantic's data validation capabilities to create robust, type-safe AI applications.

Key features include:

  • Type Safety: Built on Pydantic for automatic data validation
  • MCP Support: Native support for Model Context Protocol servers
  • Streaming: Built-in support for streaming responses
  • Async First: Designed for async/await patterns

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

The eSignatures 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 account. It provides structured and secure access to your contract templates, contracts, signers, and signing workflows, so your agent can create and send contracts, manage signers, update content, track signing status, and organize templates on your behalf.

  • Contract creation and delivery: Have your agent create contract drafts from templates or Markdown, send them for signature, or send an existing draft when it is ready.
  • Signer management: Let the agent add, update, or remove signers from editable contracts, resend signature requests, and adjust signer contact, delivery, authentication, or redirect details.
  • Template creation and collaboration: Direct your agent to create, duplicate, rename, label, or delete reusable templates, and manage the collaborators who can edit them.
  • Contract and template editing: Instruct your agent to preview and apply exact content changes, update contract placeholder values, and review template or contract Markdown.
  • Signing workflow tracking: Have your agent check contract details, current status, signers, completed field values, and signed documents when available, or withdraw an active unsigned contract.

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:
  • Python 3.9 or higher
  • A Composio account with an active API key
  • Basic familiarity with Python and async programming
2

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key. You'll need credits to use the models, or you can connect to another model provider.
  • 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

bash
pip install composio pydantic-ai python-dotenv

Install the required libraries.

What's happening:

  • composio connects your agent to external SaaS tools like eSignatures
  • pydantic-ai lets you create structured AI agents with tool support
  • python-dotenv loads your environment variables securely from a .env file
4

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates your agent to Composio's API
  • USER_ID associates your session with your account for secure tool access
  • OPENAI_API_KEY to access OpenAI LLMs
5

Import dependencies

python
import asyncio
import os
from dotenv import load_dotenv
from composio import Composio
from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStreamableHTTP

load_dotenv()
What's happening:
  • We load environment variables and import required modules
  • Composio manages connections to eSignatures
  • MCPServerStreamableHTTP connects to the eSignatures MCP server endpoint
  • Agent from Pydantic AI lets you define and run the AI assistant
6

Create a Tool Router Session

python
async def main():
    api_key = os.getenv("COMPOSIO_API_KEY")
    user_id = os.getenv("USER_ID")
    if not api_key or not user_id:
        raise RuntimeError("Set COMPOSIO_API_KEY and USER_ID in your environment")

    # Create a Composio Tool Router session for eSignatures
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["esignatures"],
    )
    url = session.mcp.url
    if not url:
        raise ValueError("Composio session did not return an MCP URL")
What's happening:
  • We're creating a Tool Router session that gives your agent access to eSignatures tools
  • The create method takes the user ID and specifies which toolkits should be available
  • The returned session.mcp.url is the MCP server URL that your agent will use
7

Initialize the Pydantic AI Agent

python
# Attach the MCP server to a Pydantic AI Agent
esignatures_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
agent = Agent(
    "openai:gpt-5",
    toolsets=[esignatures_mcp],
    instructions=(
        "You are a eSignatures assistant. Use eSignatures tools to help users "
        "with their requests. Ask clarifying questions when needed."
    ),
)
What's happening:
  • The MCP client connects to the eSignatures endpoint
  • The agent uses GPT-5 to interpret user commands and perform eSignatures operations
  • The instructions field defines the agent's role and behavior
8

Build the chat interface

python
# Simple REPL with message history
history = []
print("Chat started! Type 'exit' or 'quit' to end.\n")
print("Try asking the agent to help you with eSignatures.\n")

while True:
    user_input = input("You: ").strip()
    if user_input.lower() in {"exit", "quit", "bye"}:
        print("\nGoodbye!")
        break
    if not user_input:
        continue

    print("\nAgent is thinking...\n", flush=True)

    async with agent.run_stream(user_input, message_history=history) as stream_result:
        collected_text = ""
        async for chunk in stream_result.stream_output():
            text_piece = None
            if isinstance(chunk, str):
                text_piece = chunk
            elif hasattr(chunk, "delta") and isinstance(chunk.delta, str):
                text_piece = chunk.delta
            elif hasattr(chunk, "text"):
                text_piece = chunk.text
            if text_piece:
                collected_text += text_piece
        result = stream_result

    print(f"Agent: {collected_text}\n")
    history = result.all_messages()
What's happening:
  • The agent reads input from the terminal and streams its response
  • eSignatures API calls happen automatically under the hood
  • The model keeps conversation history to maintain context across turns
9

Run the application

python
if __name__ == "__main__":
    asyncio.run(main())
What's happening:
  • The asyncio loop launches the agent and keeps it running until you exit

Complete Code

Here's the complete code to get you started with eSignatures and Pydantic AI:

python
import asyncio
import os
from dotenv import load_dotenv
from composio import Composio
from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStreamableHTTP

load_dotenv()

async def main():
    api_key = os.getenv("COMPOSIO_API_KEY")
    user_id = os.getenv("USER_ID")
    if not api_key or not user_id:
        raise RuntimeError("Set COMPOSIO_API_KEY and USER_ID in your environment")

    # Create a Composio Tool Router session for eSignatures
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["esignatures"],
    )
    url = session.mcp.url
    if not url:
        raise ValueError("Composio session did not return an MCP URL")

    # Attach the MCP server to a Pydantic AI Agent
    esignatures_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
    agent = Agent(
        "openai:gpt-5",
        toolsets=[esignatures_mcp],
        instructions=(
            "You are a eSignatures assistant. Use eSignatures tools to help users "
            "with their requests. Ask clarifying questions when needed."
        ),
    )

    # Simple REPL with message history
    history = []
    print("Chat started! Type 'exit' or 'quit' to end.\n")
    print("Try asking the agent to help you with eSignatures.\n")

    while True:
        user_input = input("You: ").strip()
        if user_input.lower() in {"exit", "quit", "bye"}:
            print("\nGoodbye!")
            break
        if not user_input:
            continue

        print("\nAgent is thinking...\n", flush=True)

        async with agent.run_stream(user_input, message_history=history) as stream_result:
            collected_text = ""
            async for chunk in stream_result.stream_output():
                text_piece = None
                if isinstance(chunk, str):
                    text_piece = chunk
                elif hasattr(chunk, "delta") and isinstance(chunk.delta, str):
                    text_piece = chunk.delta
                elif hasattr(chunk, "text"):
                    text_piece = chunk.text
                if text_piece:
                    collected_text += text_piece
            result = stream_result

        print(f"Agent: {collected_text}\n")
        history = result.all_messages()

if __name__ == "__main__":
    asyncio.run(main())

Conclusion

You've built a Pydantic AI agent that can interact with eSignatures through Composio's Tool Router. With this setup, your agent can perform real eSignatures actions through natural language. You can extend this further by:
  • Adding other toolkits like Gmail, HubSpot, or Salesforce
  • Building a web-based chat interface around this agent
  • Using multiple MCP endpoints to enable cross-app workflows (for example, Gmail + eSignatures for workflow automation)
This architecture makes your AI agent "agent-native", able to securely use APIs in a unified, composable way without custom integrations.
TOOLS

Supported Tools

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

Add Contract Signer

Add a signer to an editable contract without automatically sending a signature request.

Add Contract Signers

Add a non-empty list of signers to an editable contract by calling the provider's singular endpoint sequentially in request order.

Add Template Collaborator

Create a name-only collaborator who can edit a template.

Create and Send Contract

Create a contract from a template or from ad-hoc Markdown and immediately send signature requests to its signers.

Create Contract Draft

Create a test or production contract draft from a template or from ad-hoc Markdown, without sending signature requests or otherwise delivering it externally.

Create Template

Create a reusable Markdown contract template.

Delete Contract Signer

Permanently remove a signer from an editable contract.

Delete Template

Permanently delete a template.

Duplicate Template

Duplicate a template with a new title plus optional placeholder replacements.

Get Contract

Get one contract's current status, details, signers, signer field values, and temporary signed-PDF URL when available.

Get Contract Content

Return the Markdown content of one contract.

Get Contract Placeholder Fields

Return the current placeholder replacements for one contract.

Get Template

Get one template's metadata, placeholder keys, and signer-field IDs.

Get Template Content

Return the Markdown content of one template.

Invite Template Collaborator

Invite a collaborator to edit a template.

List Template Collaborators

Return all collaborators who can edit one template.

List Templates

Return all templates available to the connected account.

Preview Contract Content Update

Preview the prospective Markdown from exact find-and-replace edits without mutating the contract.

Preview Template Content Update

Preview the prospective Markdown from exact find-and-replace edits without mutating the template.

Remove Template Collaborator

Remove a collaborator's permission to edit a template.

Resend Sign Request

Resend a signature request to one signer.

Send Draft Contract

Send an existing draft to its signers.

Update Contract Content

Apply exact Markdown find-and-replace edits to a contract.

Update Contract Placeholder Fields

Update selected placeholder replacements on an unsigned contract.

Update Contract Signer

Update selected contact, delivery, authentication, or redirect details for a signer without resending the contract.

Update Template

Update a template's title and/or labels without changing its Markdown content.

Update Template Content

Apply exact Markdown find-and-replace edits to a template.

Withdraw Contract

Irreversibly withdraw an active unsigned contract so it can no longer be signed.

FRAMEWORKS

How to build eSignatures MCP Agent with another framework

OpenAI Agents SDK logo

OpenAI Agents SDK

Use eSignatures MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use eSignatures MCP with Claude Agent SDK

Claude Code logo

Claude Code

Use eSignatures MCP with Claude Code

Claude Cowork logo

Claude Cowork

Use eSignatures MCP with Claude Cowork

Codex logo

Codex

Use eSignatures MCP with Codex

OpenClaw logo

OpenClaw

Use eSignatures MCP with OpenClaw

Hermes logo

Hermes

Use eSignatures MCP with Hermes

CLI logo

CLI

Use eSignatures MCP with CLI

Google ADK logo

Google ADK

Use eSignatures MCP with Google ADK

LangChain logo

LangChain

Use eSignatures MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use eSignatures MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use eSignatures MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use eSignatures MCP with LlamaIndex

CrewAI logo

CrewAI

Use eSignatures MCP with CrewAI

FAQ

Frequently asked questions

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

Yes, you can. Pydantic 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 tools.

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

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