How to integrate Documenso MCP with LangChain

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Introduction

This guide walks you through connecting Documenso to LangChain using the Composio tool router. By the end, you'll have a working Documenso agent that can send a contract to client for signature, download the latest signed nda document, list all templates for onboarding paperwork through natural language commands.

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

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

Also integrate Documenso with

TL;DR

Here's what you'll learn:
  • Get and set up your OpenAI and Composio API keys
  • Connect your Documenso project to Composio
  • Create a Tool Router MCP session for Documenso
  • Initialize an MCP client and retrieve Documenso tools
  • Build a LangChain agent that can interact with Documenso
  • Set up an interactive chat interface for testing

What is LangChain?

LangChain is a framework for developing applications powered by language models. It provides tools and abstractions for building agents that can reason, use tools, and maintain conversation context.

Key features include:

  • Agent Framework: Build agents that can use tools and make decisions
  • MCP Integration: Connect to external services through Model Context Protocol adapters
  • Memory Management: Maintain conversation history across interactions
  • Multi-Provider Support: Works with OpenAI, Anthropic, and other LLM providers

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

The Documenso MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Documenso account. It provides structured and secure access to your electronic signature workflows, so your agent can create documents, distribute them for signing, manage templates, and download signed files automatically on your behalf.

  • Automated document creation and duplication: Prompt your agent to generate new documents or make exact copies of existing ones for rapid workflow setup.
  • Seamless document distribution for signatures: Let your agent send documents to one or more recipients, kicking off secure e-signature flows without manual intervention.
  • Template management and retrieval: Ask your agent to list, fetch, or delete document templates, keeping your signing processes organized and up-to-date.
  • Download and access signed documents: Have your agent retrieve finalized, signed PDFs automatically for seamless archiving or sharing.
  • Streamlined document organization: Direct your agent to move documents between personal and team spaces, or remove unnecessary fields to keep everything tidy and current.

Supported Tools & Triggers

Tools
Create Document BetaTool to create a new document using the beta endpoint that returns a presigned URL for file upload.
Create Document FieldTool to create a single field for a document.
Create Document Fields (Bulk)Tool to create multiple fields on a document in a single operation.
Create Document RecipientTool to create a single recipient for a document.
Create Document Recipients BulkTool to create multiple recipients for a document at once.
Create Embedding Presign Token V2 BetaCreate a presign token for Documenso embedded authoring sessions.
Create EnvelopeTool to create a new envelope in Documenso.
Create Envelope AttachmentCreate a new attachment for an envelope in Documenso.
Create Envelope Items BulkTool to create multiple items for an envelope with optional file attachments.
Create Envelope Recipients BulkTool to create multiple recipients for an envelope in bulk.
Create FolderCreate a new folder in Documenso to organize documents or templates.
Create Template BetaTool to create a new template using the beta endpoint that returns a presigned URL for file upload.
Create Template FieldTool to create a single field for a template.
Create Template Fields (Bulk)Tool to create multiple fields on a template in a single operation.
Create Template RecipientTool to create a single recipient for a template.
Create Template Recipients BulkTool to create multiple recipients for a template at once.
Delete DocumentTool to delete a document.
Delete Document AttachmentTool to delete an attachment from a document.
Delete Document FieldTool to delete a single document field by ID.
Delete Document FieldsTool to delete one or more fields from a document.
Delete Document RecipientTool to delete a recipient from a document.
Delete EnvelopeTool to permanently delete an envelope.
Delete Envelope AttachmentTool to delete an attachment from an envelope.
Delete Envelope FieldTool to delete a field from an envelope.
Delete Envelope ItemTool to delete an item from an envelope.
Delete Envelope RecipientTool to delete a recipient from an envelope.
Delete FolderTool to permanently delete a folder.
Delete TemplatePermanently delete a template by its ID.
Delete Template Direct LinkDelete a direct link for a template.
Delete Template RecipientTool to delete a recipient from a template.
Delete Template V2Tool to permanently delete a template using the v2 API.
Distribute Document V2Tool to distribute a document for signing.
Distribute EnvelopeTool to distribute an envelope to recipients for signing.
Download Envelope ItemDownload an envelope item as PDF.
Download Signed DocumentDownload a completed/signed document as PDF.
Duplicate Document V2Tool to duplicate a document.
Duplicate Envelope V2Tool to duplicate an envelope with all its settings.
Duplicate TemplateTool to duplicate a template with all its settings.
Find DocumentsFind documents based on search criteria with filtering and pagination.
Find Documents V2Retrieve a paginated list of documents with optional filtering and sorting.
Find EnvelopesTool to find envelopes based on search criteria, filters, and pagination.
Find FoldersTool to find folders based on search criteria and filters.
Find TemplatesRetrieve a paginated list of templates with optional filtering and search.
Get Document By IDRetrieve complete information about a document by its ID.
Get Document FieldTool to retrieve a document field by its ID.
Get Document RecipientTool to retrieve detailed information about a document recipient by their ID.
Get Documents By IDsRetrieve multiple documents by their IDs in a single request.
Get Envelope AttachmentTool to find all attachments for a specific envelope.
Get Envelope Audit LogTool to retrieve audit logs for an envelope.
Get Envelope By IDRetrieve complete information about an envelope by its ID.
Get Envelope FieldTool to fetch an envelope field by ID.
Get Envelope RecipientTool to retrieve detailed information about an envelope recipient by their ID.
Get Envelopes By IDsTool to retrieve multiple envelopes by their IDs.
Get Template By IDRetrieve complete information about a template by its ID.
Get Template FieldTool to fetch a template field by ID.
Get Template RecipientTool to retrieve detailed information about a template recipient by their ID.
Get Templates By IDsRetrieve multiple templates by their IDs in a single request.
List TemplatesTool to list templates.
Move Document V2Tool to move a document to a team.
Redistribute Document V2Re-send signing request emails to specified recipients of a document.
Redistribute EnvelopeTool to redistribute an envelope to recipients who have not actioned it.
Remove Team Member V1Remove a member from a Documenso team.
Update Document AttachmentTool to update an existing document attachment.
Update Document FieldTool to update a single document field's properties in Documenso v2 API.
Update Document Fields BulkTool to update multiple document fields in a single operation.
Update Document Recipient V2Tool to update a document recipient using the v2 API.
Update Document V2Update document properties like title, visibility, and signing settings.
Update EnvelopeUpdate envelope properties like title, visibility, and signing settings.
Update Envelope AttachmentTool to update an existing envelope attachment.
Update Envelope Fields BulkTool to update multiple envelope fields in a single request.
Update Envelope Items BulkTool to update multiple envelope items in a single request.
Update FolderUpdate properties of an existing folder including name, pinned status, parent folder, and visibility.
Update TemplateUpdate template properties like title, visibility, and signing settings.
Update Template Fields BulkTool to update multiple template fields in a single operation.
Update Template RecipientTool to update a template recipient.
Update Template Recipients BulkTool to update multiple template recipients in a single API call.
Use Template (v2-beta)Tool to create a document from a template.

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

Prerequisites

Before starting this tutorial, make sure you have:
  • Python 3.10 or higher installed on your system
  • A Composio account with an API key
  • An OpenAI 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

pip install composio-langchain langchain-mcp-adapters langchain python-dotenv

Install the required packages for LangChain with MCP support.

What's happening:

  • composio-langchain provides Composio integration for LangChain
  • langchain-mcp-adapters enables MCP client connections
  • langchain is the core agent framework
  • python-dotenv loads environment variables

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_composio_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's API
  • COMPOSIO_USER_ID identifies the user for session management
  • OPENAI_API_KEY enables access to OpenAI's language models

Import dependencies

from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain.agents import create_agent
from dotenv import load_dotenv
from composio import Composio
import asyncio
import os

load_dotenv()
What's happening:
  • We're importing LangChain's MCP adapter and Composio SDK
  • The dotenv import loads environment variables from your .env file
  • This setup prepares the foundation for connecting LangChain with Documenso functionality through MCP

Initialize Composio client

async def main():
    composio = Composio(api_key=os.getenv("COMPOSIO_API_KEY"))

    if not os.getenv("COMPOSIO_API_KEY"):
        raise ValueError("COMPOSIO_API_KEY is not set")
    if not os.getenv("COMPOSIO_USER_ID"):
        raise ValueError("COMPOSIO_USER_ID is not set")
What's happening:
  • We're loading the COMPOSIO_API_KEY from environment variables and validating it exists
  • Creating a Composio instance that will manage our connection to Documenso tools
  • Validating that COMPOSIO_USER_ID is also set before proceeding

Create a Tool Router session

# Create Tool Router session for Documenso
session = composio.create(
    user_id=os.getenv("COMPOSIO_USER_ID"),
    toolkits=['documenso']
)

url = session.mcp.url
What's happening:
  • We're creating a Tool Router session that gives your agent access to Documenso 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
  • This approach allows the agent to dynamically load and use Documenso tools as needed

Configure the agent with the MCP URL

client = MultiServerMCPClient({
    "documenso-agent": {
        "transport": "streamable_http",
        "url": session.mcp.url,
        "headers": {
            "x-api-key": os.getenv("COMPOSIO_API_KEY")
        }
    }
})

tools = await client.get_tools()

agent = create_agent("gpt-5", tools)
What's happening:
  • We're creating a MultiServerMCPClient that connects to our Documenso MCP server via HTTP
  • The client is configured with a name and the URL from our Tool Router session
  • get_tools() retrieves all available Documenso tools that the agent can use
  • We're creating a LangChain agent using the GPT-5 model

Set up interactive chat interface

conversation_history = []

print("Chat started! Type 'exit' or 'quit' to end the conversation.\n")
print("Ask any Documenso related question or task to the agent.\n")

while True:
    user_input = input("You: ").strip()

    if user_input.lower() in ['exit', 'quit', 'bye']:
        print("\nGoodbye!")
        break

    if not user_input:
        continue

    conversation_history.append({"role": "user", "content": user_input})
    print("\nAgent is thinking...\n")

    response = await agent.ainvoke({"messages": conversation_history})
    conversation_history = response['messages']
    final_response = response['messages'][-1].content
    print(f"Agent: {final_response}\n")
What's happening:
  • We initialize an empty conversation_history list to maintain context across interactions
  • A while loop continuously accepts user input from the command line
  • When a user types a message, it's added to the conversation history and sent to the agent
  • The agent processes the request using the ainvoke() method with the full conversation history
  • Users can type 'exit', 'quit', or 'bye' to end the chat session gracefully

Run the application

if __name__ == "__main__":
    asyncio.run(main())
What's happening:
  • We call the main() function using asyncio.run() to start the application

Complete Code

Here's the complete code to get you started with Documenso and LangChain:

from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain.agents import create_agent
from dotenv import load_dotenv
from composio import Composio
import asyncio
import os

load_dotenv()

async def main():
    composio = Composio(api_key=os.getenv("COMPOSIO_API_KEY"))
    
    if not os.getenv("COMPOSIO_API_KEY"):
        raise ValueError("COMPOSIO_API_KEY is not set")
    if not os.getenv("COMPOSIO_USER_ID"):
        raise ValueError("COMPOSIO_USER_ID is not set")
    
    session = composio.create(
        user_id=os.getenv("COMPOSIO_USER_ID"),
        toolkits=['documenso']
    )

    url = session.mcp.url
    
    client = MultiServerMCPClient({
        "documenso-agent": {
            "transport": "streamable_http",
            "url": url,
            "headers": {
                "x-api-key": os.getenv("COMPOSIO_API_KEY")
            }
        }
    })
    
    tools = await client.get_tools()
  
    agent = create_agent("gpt-5", tools)
    
    conversation_history = []
    
    print("Chat started! Type 'exit' or 'quit' to end the conversation.\n")
    print("Ask any Documenso related question or task to the agent.\n")
    
    while True:
        user_input = input("You: ").strip()
        
        if user_input.lower() in ['exit', 'quit', 'bye']:
            print("\nGoodbye!")
            break
        
        if not user_input:
            continue
        
        conversation_history.append({"role": "user", "content": user_input})
        print("\nAgent is thinking...\n")
        
        response = await agent.ainvoke({"messages": conversation_history})
        conversation_history = response['messages']
        final_response = response['messages'][-1].content
        print(f"Agent: {final_response}\n")

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

Conclusion

You've successfully built a LangChain agent that can interact with Documenso through Composio's Tool Router.

Key features of this implementation:

  • Dynamic tool loading through Composio's Tool Router
  • Conversation history maintenance for context-aware responses
  • Async Python provides clean, efficient execution of agent workflows
You can extend this further by adding error handling, implementing specific business logic, or integrating additional Composio toolkits to create multi-app workflows.

How to build Documenso MCP Agent with another framework

FAQ

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

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

Can I use Tool Router MCP with LangChain?

Yes, you can. LangChain 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 Documenso tools.

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

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

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