How to integrate Ignisign MCP with Pydantic AI

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Introduction

This guide walks you through connecting Ignisign to Pydantic AI using the Composio tool router. By the end, you'll have a working Ignisign agent that can start a new signature request for a contract, add a new signer to this application, delete a completed document by its id, create a webhook to track signature events through natural language commands.

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

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

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 Ignisign
  • 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 Ignisign 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 Ignisign MCP server, and what's possible with it?

The Ignisign MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Ignisign account. It provides structured and secure access to your electronic signature workflows, so your agent can perform actions like sending signature requests, managing documents, onboarding signers, and handling signature operations on your behalf.

  • Automated signature request management: Let your agent create, cancel, or delete signature requests, streamlining the entire e-signature process from start to finish.
  • Document initialization and deletion: Have the agent initialize new documents for signing or permanently delete documents when they're no longer needed.
  • Signer onboarding and removal: Effortlessly add new signers to your application environment or remove existing ones as your workflows change.
  • Webhook endpoint management: Allow your agent to create or delete webhook endpoints, enabling real-time notifications and integrations for signature events.
  • Application context retrieval: Fetch global application settings and environment configurations so your agent always works with up-to-date information.

Supported Tools & Triggers

Tools
Ignisign API AuthenticationTool to authenticate an application over Ignisign API and retrieve a JWT.
Cancel Signature RequestTool to cancel a signature request.
Initialize DocumentTool to initialize a document for a signature request.
Create SignerTool to create a new signer.
Create Webhook EndpointTool to create a new webhook endpoint for an application.
Delete DocumentTool to delete a specific document by its ID.
Delete Ignisign Signature RequestTool to delete a signature request.
Delete SignerTool to delete a signer.
Delete Webhook EndpointTool to delete a specific webhook endpoint.
Get application contextTool to retrieve the global context of an application.
Get Document InformationTool to retrieve document metadata by ID.
Get Missing Signer InputsTool to determine missing inputs needed for a signer in a specific signature profile.
Get Signature Request DetailsTool to retrieve detailed information for a specific signature request.
Get Signature Request DocumentTool to retrieve the document associated with a specific signature request.
Get Signature RequestsTool to retrieve a paginated list of signature requests for an application.
Get Signature Request StatusTool to retrieve the current status of a specific signature request.
Get Signed DocumentTool to download the signed document (signature proof) for a signature request.
Get Signer Creation ConstraintsTool to retrieve input constraints required to create a signer for a specific signature profile.
Get Signer Input ConstraintsTool to get signer input constraints.
Get Signer InputsTool to retrieve inputs provided by a signer for a signature request.
Get Signer ProfileTool to retrieve a signer profile.
Get Signer ProfilesTool to retrieve signer profiles.
Get Webhook DetailsTool to retrieve details of a specific webhook endpoint.
Get WebhooksTool to list all webhook endpoints configured for an application environment.
Close Ignisign Signature RequestTool to close an active signature request.
Update SignerTool to update details of an existing signer.
Initialize Ignisign Signature RequestTool to initialize a new signature request.
List DocumentsTool to retrieve documents linked to a signature request.
Provide Document Content Data JSONTool to provide JSON content for a document.
Provide Document Content FileTool to provide file content for a document.
Provide Document Content Private FileTool to provide private content for a document via its SHA-256 hash.
Publish Signature RequestTool to publish a draft signature request.
Search SignersTool to search for signers within an application.
Update Document InformationTool to update document metadata.
Update Signature RequestTool to partially update a signature request in DRAFT state.
Update Webhook EndpointTool to update an existing webhook endpoint.

What is the Composio tool router, and how does it fit here?

What is Tool Router?

Composio's Tool Router 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 Tool Router

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Tool Router works

The Tool Router 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 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

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.

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 Ignisign
  • pydantic-ai lets you create structured AI agents with tool support
  • python-dotenv loads your environment variables securely from a .env file

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

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 Ignisign
  • MCPServerStreamableHTTP connects to the Ignisign MCP server endpoint
  • Agent from Pydantic AI lets you define and run the AI assistant

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 Ignisign
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["ignisign"],
    )
    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 Ignisign 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

Initialize the Pydantic AI Agent

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

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 Ignisign.\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
  • Ignisign API calls happen automatically under the hood
  • The model keeps conversation history to maintain context across turns

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 Ignisign 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 Ignisign
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["ignisign"],
    )
    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
    ignisign_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
    agent = Agent(
        "openai:gpt-5",
        toolsets=[ignisign_mcp],
        instructions=(
            "You are a Ignisign assistant. Use Ignisign 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 Ignisign.\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 Ignisign through Composio's Tool Router. With this setup, your agent can perform real Ignisign 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 + Ignisign for workflow automation)
This architecture makes your AI agent "agent-native", able to securely use APIs in a unified, composable way without custom integrations.

How to build Ignisign MCP Agent with another framework

FAQ

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

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

Can I use Tool Router MCP with Pydantic AI?

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 Ignisign tools.

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

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

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