How to connect Customjs to Claude Cowork

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Introduction

Cowork is Anthropic's AI agent for knowledge work. Think of it as Claude Code for everything else. It works autonomously with your computer, local files, and applications to accomplish complex tasks.

This guide walks you through the easiest and most secure way to connect your Customjs account to Cowork via Composio Connect, enabling it to convert this HTML invoice to PDF file, take a screenshot of your company homepage, merge these three PDF reports into one, and more such actions on your behalf without compromising your account security.

Also integrate Customjs with

Connecting Customjs to Claude 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 Cowork

4. Connect your Customjs account

Back in Cowork, ask the agent to connect to Customjs or give it any Customjs-related task.

For example, ask Cowork to:

  • "Convert this HTML invoice to PDF file"
  • "Take a screenshot of your company homepage"
  • "Merge these three PDF reports into one"

It will prompt you to authenticate and authorize access.

That's it. Composio's tools are now available in Cowork, and your Customjs account is ready to use.

What is Claude Cowork?

Claude Cowork is Anthropic's agent for general knowledge work. It can use your computer, files, and connected applications to complete longer-running tasks across your work tools.

With Composio Connect, Cowork can securely access apps like Customjs through MCP without you sharing account credentials directly with the agent.

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

The Customjs MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Customjs account. It provides structured and secure access to your Customjs automations, so your agent can convert HTML to PDFs and images, capture website screenshots, merge PDF files, and run custom browser scripts on your behalf.

  • HTML to PDF and PNG conversion: Instantly generate high-quality PDFs or PNG images from any HTML markup or template using agent commands.
  • Automated webpage screenshot capture: Have your agent take precise, up-to-date screenshots of any public webpage for documentation, monitoring, or reporting.
  • PDF merging and file handling: Let your agent combine multiple PDF files into a single document, perfect for reports or document consolidation tasks.
  • Headless browser automation with Puppeteer: Empower your agent to execute custom Puppeteer scripts—scraping data or capturing advanced browser screenshots as PNGs.
  • Secure API key authentication: Ensure that all actions are performed securely by verifying your Customjs API key through the agent-managed authentication flow.

Supported Tools & Triggers

Tools
Authenticate CustomJS API KeyTool to authenticate a CustomJS API key.
Convert HTML to PDFTool to convert HTML to a PDF document.
Convert HTML to PNGTool to convert HTML string to PNG image.
Capture webpage screenshotTool to capture a screenshot of a webpage.
Merge multiple PDFs into oneTool to merge multiple PDF files into a single PDF.
Run Puppeteer ScriptTool to run a Puppeteer script and capture a screenshot.

How to build Customjs MCP Agent with another framework

FAQ

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

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

Can I use Tool Router MCP with Claude Cowork?

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 Customjs tools.

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

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

Used by agents from

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HubSpot
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Context
Letta
glean
HubSpot
Agent.ai
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Never worry about agent reliability

We handle tool reliability, observability, and security so you never have to second-guess an agent action.