How to integrate Api2pdf MCP with LangChain

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Introduction

This guide walks you through connecting Api2pdf to LangChain using the Composio tool router. By the end, you'll have a working Api2pdf agent that can merge monthly invoices into one pdf, extract specific pages from a large pdf, add custom header and footer to document, convert pdf report to html for web use through natural language commands.

This guide will help you understand how to give your LangChain agent real control over a Api2pdf account through Composio's Api2pdf 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:
  • Get and set up your OpenAI and Composio API keys
  • Connect your Api2pdf project to Composio
  • Create a Tool Router MCP session for Api2pdf
  • Initialize an MCP client and retrieve Api2pdf tools
  • Build a LangChain agent that can interact with Api2pdf
  • 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 Api2pdf MCP server, and what's possible with it?

The Api2pdf MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Api2pdf account. It provides structured and secure access to powerful PDF generation and manipulation features, so your agent can generate PDFs from HTML or URLs, merge or optimize documents, extract or reorder pages, and more—automatically and on your behalf.

  • PDF generation from web content: Instruct your agent to convert HTML or URLs into high-quality PDFs using engines like wkhtmltopdf or Headless Chrome.
  • Merge and optimize PDFs: Have your agent combine multiple PDFs into a single file or optimize existing documents to reduce file size without sacrificing quality.
  • Advanced PDF manipulation: Direct your agent to extract specific pages, reorder existing pages, or add custom headers and footers for consistent branding or page numbering.
  • Barcode and QR code generation: Let your agent instantly create barcode or QR code images from any text value, ready to embed in documents or use elsewhere.
  • Document conversion and preview: Ask your agent to convert PDFs to HTML with LibreOffice or generate thumbnail previews for quick visual reference.

Supported Tools & Triggers

Tools
Add Header FooterTool to add headers and footers to a pdf document.
Delete PDFTool to delete a previously generated pdf.
Extract PDF PagesTool to extract specific pages from a pdf document.
LibreOffice PDF to HTMLTool to convert a pdf document to html using libreoffice.
LibreOffice ThumbnailTool to generate a thumbnail image of a document using libreoffice.
Merge PDFsTool to merge multiple pdf documents into a single pdf.
Optimize PDFTool to optimize a pdf document to reduce file size while maintaining quality.
Reorder PDF PagesTool to reorder pages of a pdf document.
Generate Barcode or QR CodeTool to generate barcodes or qr codes using zebra crossing (zxing).

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 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 Api2pdf 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 Api2pdf tools
  • Validating that COMPOSIO_USER_ID is also set before proceeding

Create a Tool Router session

# Create Tool Router session for Api2pdf
session = composio.create(
    user_id=os.getenv("COMPOSIO_USER_ID"),
    toolkits=['api2pdf']
)

url = session.mcp.url
What's happening:
  • We're creating a Tool Router session that gives your agent access to Api2pdf 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 Api2pdf tools as needed

Configure the agent with the MCP URL

client = MultiServerMCPClient({
    "api2pdf-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 Api2pdf MCP server via HTTP
  • The client is configured with a name and the URL from our Tool Router session
  • get_tools() retrieves all available Api2pdf 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 Api2pdf 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 Api2pdf 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=['api2pdf']
    )

    url = session.mcp.url
    
    client = MultiServerMCPClient({
        "api2pdf-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 Api2pdf 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 Api2pdf 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 Api2pdf MCP Agent with another framework

OpenAI Agents SDK

OpenAI Agents SDK

Use Api2pdf MCP with OpenAI Agents SDK

Claude Agent SDK

Claude Agent SDK

Use Api2pdf MCP with Claude Agent SDK

Google ADK

Google ADK

Use Api2pdf MCP with Google ADK

Vercel AI SDK

Vercel AI SDK

Use Api2pdf MCP with Vercel AI SDK

Mastra AI

Mastra AI

Use Api2pdf MCP with Mastra AI

LlamaIndex

LlamaIndex

Use Api2pdf MCP with LlamaIndex

CrewAI

CrewAI

Use Api2pdf MCP with CrewAI

FAQ

What are the differences in Tool Router MCP and Api2pdf MCP?

With a standalone Api2pdf MCP server, the agents and LLMs can only access a fixed set of Api2pdf tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Api2pdf 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 Api2pdf tools.

Can I manage the permissions and scopes for Api2pdf while using Tool Router?

Yes, absolutely. You can configure which Api2pdf 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 Api2pdf data and credentials are handled as safely as possible.

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Context
ASU
Letta
glean
HubSpot
Agent.ai
Altera
DataStax
Entelligence
Rolai
Context
ASU
Letta
glean
HubSpot
Agent.ai
Altera
DataStax
Entelligence
Rolai

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