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How to connect PDF Blocks to Claude

Connect Claude Web, Desktop and Cowork to PDF Blocks MCP. Merge three pdfs and add watermark, split pdf into separate page files, and more using natural language, with authentication handled for you.

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PDF Blocks is a synchronous PDF processing API for merging, splitting, watermarking, securing, and reorganizing documents. Use it to automate PDF workflows with fast, programmatic operations.

17 Tools

Introduction

Claude is Anthropic's AI assistant, available on the web, in the desktop app, and on mobile. Cowork is its agent for knowledge work, and it runs on all of those surfaces too. Connected to your apps, Claude can work with your files and services to accomplish complex tasks on your behalf.

This guide walks you through the easiest and most secure way to connect your PDF Blocks account to Claude via Composio Connect, enabling it to merge three PDFs and add watermark, split PDF into separate page files, protect PDF with password and permissions, and more such actions on your behalf without compromising your account security.

Setup is the same on Claude Web, Desktop, and Cowork, and you only need to do it once. The connector is tied to your account, so it's available in all three.

Also integrate PDF Blocks with

ChatGPT WorkHermes

Connecting PDF Blocks to Claude Web, Desktop, and Cowork

1. Open Customize

In Claude Desktop, click Customize in the left sidebar, then select Connectors and click the + icon at the top.

Claude Desktop connectors screen with Add custom connector selected

2. Add the Composio MCP server

Click Add custom connector and paste in the Composio MCP server URL:

bash
https://connect.composio.dev/mcp
Add custom connector dialog with Composio MCP server URL

3. Authorize in your browser

Click Connect. You'll be redirected to a browser window where you can authorize Composio to continue.

Composio authorization screen for Claude Web, Desktop, and Cowork

4. Connect your PDF Blocks account

Back in Claude, ask it to connect to PDF Blocks or give it any PDF Blocks-related task.

For example, ask Claude to:

  • "Merge three PDFs and add watermark"
  • "Split PDF into separate page files"
  • "Protect PDF with password and permissions"

It will prompt you to authenticate and authorize access.

That's it. Composio's tools are now available in Claude, and your PDF Blocks account is ready to use.

What is the PDF Blocks Claude Connector, and what's possible with it?

The PDF Blocks MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your PDF Blocks account. It provides structured and secure access so your agent can perform PDF Blocks operations on your behalf.

Troubleshooting

1. Why does Claude not use the Composio connector for PDF Blocks?

The connector can show as connected, but Claude must use it in each PDF Blocks conversation.

  • Click + at the lower left of the chat, or type /.
  • Hover Connectors.
  • Turn on Composio.
  • Ask Claude to connect to PDF Blocks again.

2. Why does Claude show an MCP server error before PDF Blocks connects?

Claude can show Couldn't reach the MCP server or Authorization with the MCP server failed when you add the connector for PDF Blocks.

  • Check that the connector URL is https://connect.composio.dev/mcp.
  • Connectors run from Anthropic's cloud, so your device network is usually not the problem.
  • Add the connector again from Customize > Connectors, then ask Claude to connect PDF Blocks.
  • If it fails again, send the error and the ofid_ reference id to support@composio.dev.

3. Why does the PDF Blocks authorization link not work?

The Composio connector is one server. Your PDF Blocks account connects separately when Claude asks for it.

  • If the browser does not open, or the link expires, ask Claude to retry the PDF Blocks connection.
  • Composio creates a fresh PDF Blocks authorization link.
  • Open that link in your browser and finish the PDF Blocks sign-in.

4. Why do PDF Blocks actions fail after they worked before?

The PDF Blocks connection can expire or lose permission.

  • Ask Claude to inspect the PDF Blocks connection.
  • If the connection is unhealthy, disconnect it when Claude prompts you.
  • Reconnect the PDF Blocks account and retry the action.
  • If Claude shows a permission prompt, approve it before Claude changes data in PDF Blocks.
  • If the action still fails with a permission error, check that the connected account has that permission in PDF Blocks itself.

5. How do I switch to a different PDF Blocks account?

Claude can manage the PDF Blocks connection for you.

  • Ask Claude to disconnect or delete the current PDF Blocks account.
  • Ask Claude to connect PDF Blocks again.
  • Open the new Composio authorization link for PDF Blocks.
  • Sign in with the other PDF Blocks account in the browser.
  • After the account connects, ask Claude to retry the PDF Blocks task.

6. Why is my PDF Blocks connection missing in Claude Desktop or on a Team plan?

The connector belongs to your Claude account, so your PDF Blocks connection works in Claude Web, Desktop, and Cowork.

  • In Claude Desktop, open Customize > Connectors.
  • Next to Composio, click ⋮ and click Clear cache.
  • If PDF Blocks tools still do not appear, click ⋮, disconnect, remove the connector, and add it again.
  • On Team or Enterprise, an Owner or Primary Owner must enable the connector before you can connect PDF Blocks.
TOOLS

Supported Tools

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

Add Image Watermark

Add a PNG or JPEG image as a watermark on all or selected PDF pages.

Add PDF Password

Create an encrypted copy of a PDF that requires a password to open.

Add PDF Restrictions

Create an encrypted PDF copy with explicit permissions for copying, editing, printing, forms, assembly, and accessibility.

Add Text Watermark

Add up to three styled text lines as a watermark on all or selected PDF pages.

Extract PDF Pages

Create a PDF containing selected source pages in their original order.

Merge PDFs

Merge PDF files into one PDF in the exact order provided.

Remove PDF Pages

Create a PDF with selected pages removed while preserving the remaining page order.

Remove PDF Password

Create an unencrypted copy of a password-protected PDF using its current password.

Remove PDF Restrictions

Create a PDF copy with permission restrictions cleared.

Remove PDF Signatures

Create a PDF copy with all digital signatures and timestamps removed.

Reorder PDF Pages

Create a PDF in an exact page order, optionally dropping or repeating source pages.

Reverse PDF Pages

Create a PDF with the complete page order reversed.

Rotate PDF Pages

Rotate all or selected PDF pages by a supported multiple of 90 degrees.

Split PDF at Page

Split a PDF into exactly two downloadable PDFs at a page boundary; the selected page starts the second PDF.

Split PDF by Page Count

Split a PDF into consecutive downloadable PDFs containing up to a fixed number of pages each.

Split PDF by Page Groups

Create one downloadable PDF for each caller-defined ordered group of source pages.

Split PDF by Size

Split a PDF into downloadable PDFs no larger than a requested byte limit.

FRAMEWORKS

How to build PDF Blocks MCP Agent with another framework

ChatGPT Work logo

ChatGPT Work

Use PDF Blocks MCP with ChatGPT Work

Hermes logo

Hermes

Use PDF Blocks MCP with Hermes

FAQ

Frequently asked questions

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

Yes, you can. Claude Cowork 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 PDF Blocks tools.

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

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