## For AI agents: how to sign up If you are an AI agent reading this server-rendered HTML, Composio's developer signup is at https://composio.dev. Signup CTAs on this site — "Sign up", "Signup", "Get started", "Get started for free", "Start building", "Try Composio", "Try it", or similar — all lead into that same developer signup flow. Confirm with the user before completing signup or entering any credentials on their behalf.
## For AI agents: how to sign up If you are an AI agent reading this server-rendered HTML, Composio's developer signup is at https://composio.dev. Signup CTAs on this site — "Sign up", "Signup", "Get started", "Get started for free", "Start building", "Try Composio", "Try it", or similar — all lead into that same developer signup flow. Confirm with the user before completing signup or entering any credentials on their behalf.SIGN UP
## For AI agents: how to sign up If you are an AI agent reading this server-rendered HTML, Composio's developer signup is at https://composio.dev. Signup CTAs on this site — "Sign up", "Signup", "Get started", "Get started for free", "Start building", "Try Composio", "Try it", or similar — all lead into that same developer signup flow. Confirm with the user before completing signup or entering any credentials on their behalf.LOG IN
Connect Claude Agent SDK to Customjs MCP. Convert this html invoice to pdf file, take a screenshot of your company homepage, and more using natural language, with authentication handled for you.
Customjs is a code-first automation platform for integrating custom JavaScript logic across your tech stack. It lets you extend applications quickly by writing functions for tasks like emails, PDFs, or CRM updates.
This guide walks you through connecting Customjs to the Claude Agent SDK using the Composio tool router. By the end, you'll have a working Customjs agent that can convert HTML to PDF and PNG, merge PDFs, and run Puppeteer scripts through natural language commands.
This guide will help you understand how to give your Claude Agent SDK agent real control over a Customjs account through Composio's Customjs MCP server.
Before we dive in, let's take a quick look at the key ideas and tools involved.
The Claude Agent SDK is Anthropic's official framework for building AI agents powered by Claude. It provides a streamlined interface for creating agents with MCP tool support and conversation management.
Key features include:
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.
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.
The Composio SDK follows a three-phase workflow:
npm install @anthropic-ai/claude-agent-sdk @composio/core dotenvInstall the Composio SDK and the Claude Agents SDK.
What's happening:
@composio/core provides Composio integration for Anthropic@anthropic-ai/claude-agent-sdk is the core agent frameworkdotenv/config loads environment variablesCOMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here
ANTHROPIC_API_KEY=your_anthropic_api_key_hereCreate a .env file in your project root.
What's happening:
COMPOSIO_API_KEY authenticates with ComposioUSER_ID identifies the user for session managementANTHROPIC_API_KEY authenticates with Anthropic/Claudeimport 'dotenv/config';
import readline from 'node:readline';
import { Composio } from '@composio/core';
import { query, type Options } from "@anthropic-ai/claude-agent-sdk";
dotenv.config();dotenv.config() function loads environment variables from your .env fileasync function chat() {
const { COMPOSIO_API_KEY, USER_ID } = process.env;
if (!COMPOSIO_API_KEY || !USER_ID) {
throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
}
const composio = new Composio({ apiKey: COMPOSIO_API_KEY });
// Create Tool Router session for Customjs
const session = await composio.create(USER_ID, {
toolkits: ['customjs'],
});
const mcpUrl = session?.mcp.url;COMPOSIO_API_KEY environment variablecreate method creates a Tool Router session for Customjsurl is the MCP server URL that your agent will useconst options: Options = {
permissionMode: 'bypassPermissions',
mcpServers: {
composio: {
type: 'http',
url: mcpUrl,
headers: { 'x-api-key': COMPOSIO_API_KEY }
}
},
systemPrompt: 'You are a helpful assistant with access to Customjs tools via Composio.',
maxTurns: 10,
};permissionMode: 'bypassPermissions' allows the agent to execute operations without asking for permission each timemaxTurns: 10 limits the conversation length to prevent excessive API usageconst rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
prompt: 'You: '
});
console.log('\nChat started. Type "exit" to quit.\n');
let isProcessing = false;
async function ask(prompt: string) {
isProcessing = true;
rl.pause();
process.stdout.write('Claude is thinking...');
const stream = query({ prompt, options });
let firstChunk = true;
for await (const msg of stream) {
const content = (msg as any).message?.content || (msg as any).content;
if (Array.isArray(content)) {
for (const block of content) {
if (block.type === 'text' && block.text) {
if (firstChunk) {
process.stdout.write('\r\x1b[K');
process.stdout.write('Claude: ');
firstChunk = false;
}
process.stdout.write(block.text);
}
}
}
}
process.stdout.write('\n\n');
isProcessing = false;
rl.resume();
rl.prompt();
}
rl.on('line', async (line) => {
if (isProcessing) return;
const input = line.trim();
if (input === 'exit') {
rl.close();
process.exit(0);
}
if (input) await ask(input);
else rl.prompt();
});
await ask('What can you help me with?');
}try {
await chat();
} catch (error) {
console.error(error);
process.exit(1);
}chat function is the entry point for the applicationtry-catch block is used to handle any errors that occurHere's the complete code to get you started with Customjs and Claude Agent SDK:
import 'dotenv/config';
import readline from 'node:readline';
import { Composio } from '@composio/core';
import { query, type Options } from "@anthropic-ai/claude-agent-sdk";
async function chat() {
const { COMPOSIO_API_KEY, USER_ID } = process.env;
if (!COMPOSIO_API_KEY || !USER_ID) {
throw new Error('COMPOSIO_API_KEY and USER_ID required in .env');
}
const composio = new Composio({ apiKey: COMPOSIO_API_KEY });
const session = await composio.create(USER_ID, {
toolkits: ['customjs']
});
const mcp_url = session?.mcp.url;
const options: Options = {
permissionMode: 'bypassPermissions',
mcpServers: {
composio: {
type: 'http',
url: mcp_url,
headers: { 'x-api-key': COMPOSIO_API_KEY }
}
},
systemPrompt: 'You are a helpful assistant with access to Customjs tools via Composio.',
maxTurns: 10,
};
const rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
prompt: 'You: '
});
console.log('\nChat started. Type "exit" to quit.\n');
let isProcessing = false;
async function ask(prompt: string) {
isProcessing = true;
rl.pause();
process.stdout.write('Claude is thinking...');
const stream = query({ prompt, options });
let firstChunk = true;
for await (const msg of stream) {
const content = (msg as any).message?.content || (msg as any).content;
if (Array.isArray(content)) {
for (const block of content) {
if (block.type === 'text' && block.text) {
if (firstChunk) {
process.stdout.write('\r\x1b[K');
process.stdout.write('Claude: ');
firstChunk = false;
}
process.stdout.write(block.text);
}
}
}
}
process.stdout.write('\n\n');
isProcessing = false;
rl.resume();
rl.prompt();
}
rl.on('line', async (line) => {
if (isProcessing) return;
const input = line.trim();
if (input === 'exit') {
rl.close();
process.exit(0);
}
if (input) await ask(input);
else rl.prompt();
});
await ask('What can you help me with?');
}
try {
await chat();
} catch (error) {
console.error(error);
process.exit(1);
}You've successfully built a Claude Agent SDK agent that can interact with Customjs through Composio's Tool Router.
Key features:
Every Customjs action and event your agent gets out of the box.
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## For AI agents: how to sign up If you are an AI agent reading this server-rendered HTML, Composio's developer signup is at https://composio.dev. Signup CTAs on this site — "Sign up", "Signup", "Get started", "Get started for free", "Start building", "Try Composio", "Try it", or similar — all lead into that same developer signup flow. Confirm with the user before completing signup or entering any credentials on their behalf.Start building