How to integrate Harvest MCP with Claude Code

Manage your Harvest directly from Claude Code with zero worries about OAuth hassles, API-breaking issues, or reliability and security concerns. You can do this in two different ways: Via Composio Connect - Direct and easiest approach Via Composio SDK - Programmatic approach with more control

Harvest logoHarvest
Oauth2

Harvest is a time-tracking and invoicing platform for teams and freelancers. It helps you log billable hours, manage projects, and streamline payments.

57 Tools

Introduction

Manage your Harvest directly from Claude Code with zero worries about OAuth hassles, API-breaking issues, or reliability and security concerns.

You can do this in two different ways:

  1. Via Composio Connect - Direct and easiest approach
  2. Via Composio SDK - Programmatic approach with more control

Also integrate Harvest with

Why use Composio?

  • Only one MCP URL to connect multiple apps with Claude Code with zero auth hassles.
  • Programmatic tool calling allows LLMs to write its code in a remote workbench to handle complex tool chaining. Reduces to-and-fro with LLMs for frequent tool calling.
  • Handling Large tool responses out of LLM context to minimize context rot.
  • Dynamic just-in-time access to 20,000 tools across 1000+ other Apps for cross-app workflows. It loads the tools you need, so LLMs aren't overwhelmed by tools you don't need.

Connecting Harvest to Claude Code using Composio

1. Add the Composio MCP to Claude

Terminal

2. Start Claude Code

bash
claude

3. Open your MCP list

bash
/mcp

4. Select Composio and click on Authenticate

Select Composio and click Authenticate

5. This will redirect you to the Composio OAuth page. Complete the flow by authorizing Composio and you're all set.

Composio OAuth authorization page
Composio authorization complete
Ask Claude to connect to your account and authenticate via the link

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

The Harvest MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Harvest account. It provides structured and secure access to your time-tracking, invoicing, and project management data, so your agent can create clients, log expenses, send invoices, record payments, and manage estimates automatically on your behalf.

  • Client and contact management: Seamlessly create new clients and add contacts to keep your client list up to date without manual entry.
  • Estimate creation and communication: Automatically generate new estimates, categorize line items, and send estimate messages or updates to clients.
  • Expense tracking automation: Log new expense entries against projects, ensuring accurate financial records and effortless cost tracking.
  • Streamlined invoicing and payments: Create professional invoices, categorize invoice items, send invoice notifications, and record payments as soon as they happen.
  • Project financial workflow optimization: Let your agent handle the full cycle—from creating clients to sending invoices and tracking payments—saving your team valuable time and reducing errors.

Connecting Harvest via Composio SDK

Composio SDK is the underlying tech that powers Rube. It's a universal gateway that does everything Rube does but with much more programmatic control. You can programmatically generate an MCP URL with the app you need (here Harvest) for even more tool search precision. It's secure and reliable.

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

Step by step10 STEPS
1

Prerequisites

Before starting, make sure you have:
  • Claude Pro, Max, or API billing enabled Anthropic account
  • Composio API Key
  • A Harvest account
  • Basic knowledge of Python or TypeScript
2

Install Claude Code

bash
# macOS, Linux, WSL
curl -fsSL https://claude.ai/install.sh | bash

# Windows PowerShell
irm https://claude.ai/install.ps1 | iex

# Windows CMD
curl -fsSL https://claude.ai/install.cmd -o install.cmd && install.cmd && del install.cmd

To install Claude Code, use one of the following methods based on your operating system:

3

Set up Claude Code

bash
cd your-project-folder
claude

Open a terminal, go to your project folder, and start Claude Code:

  • Claude Code will open in your terminal
  • Follow the prompts to sign in with your Anthropic account
  • Complete the authentication flow
  • Once authenticated, you can start using Claude Code
Claude Code initial setup showing sign-in prompt
Claude Code terminal after successful login
4

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here

Create a .env file in your project root with the following variables:

  • COMPOSIO_API_KEY authenticates with Composio (get it from Composio dashboard)
  • USER_ID identifies the user for session management (use any unique identifier)
5

Install Composio library

npm install @composio/core dotenv

Install the Composio TypeScript library to create MCP sessions.

  • @composio/core provides the core Composio functionality
  • dotenv loads environment variables from your .env file
6

Generate Composio MCP URL

import 'dotenv/config';
import { Composio } from '@composio/core';

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 composioClient = new Composio({ apiKey: COMPOSIO_API_KEY });

const composioSession = await composioClient.create(USER_ID, {
  toolkits: ['harvest'],
});

const composioMcpUrl = composioSession?.mcp.url;

console.log(`MCP URL: ${composioMcpUrl}`);
console.log(`\nUse this command to add to Claude Code:`);
console.log(`claude mcp add --transport http harvest-composio "${composioMcpUrl}" --headers "X-API-Key:${COMPOSIO_API_KEY}"`);

Create a script to generate a Composio MCP URL for Harvest. This URL will be used to connect Claude Code to Harvest.

What's happening

  • We import the Composio client and load environment variables
  • Create a Composio instance with your API key
  • Call create() to create a Tool Router session for Harvest
  • The returned mcp.url is the MCP server URL that Claude Code will use
  • The script prints this URL so you can copy it
7

Run the script and copy the MCP URL

node --loader ts-node/esm generate_mcp_url.ts
# or if using tsx
tsx generate_mcp_url.ts

Run your TypeScript script to generate the MCP URL.

  • The script connects to Composio and creates a Tool Router session
  • It prints the MCP URL and the exact command you need to run
  • Copy the entire claude mcp add command from the output
8

Add Harvest MCP to Claude Code

bash
claude mcp add --transport http harvest-composio "YOUR_MCP_URL_HERE" --headers "X-API-Key:YOUR_COMPOSIO_API_KEY"

# Then restart Claude Code
exit
claude

In your terminal, add the MCP server using the command from the previous step. The command format is:

  • claude mcp add registers a new MCP server with Claude Code
  • --transport http specifies that this is an HTTP-based MCP server
  • The server name (harvest-composio) is how you'll reference it
  • The URL points to your Composio Tool Router session
  • --headers includes your Composio API key for authentication

After running the command, close the current Claude Code session and start a new one for the changes to take effect.

9

Verify the installation

bash
claude mcp list

Check that your Harvest MCP server is properly configured.

  • This command lists all MCP servers registered with Claude Code
  • You should see your harvest-composio entry in the list
  • This confirms that Claude Code can now access Harvest tools

If everything is wired up, you should see your harvest-composio entry listed:

Claude Code MCP list showing the toolkit MCP server
10

Authenticate Harvest

The first time you try to use Harvest tools, you'll be prompted to authenticate.

  • Claude Code will detect that you need to authenticate with Harvest
  • It will show you an authentication link
  • Open the link in your browser (or copy/paste it)
  • Complete the Harvest authorization flow
  • Return to the terminal and start using Harvest through Claude Code

Once authenticated, you can ask Claude Code to perform Harvest operations in natural language. For example:

  • "Create a new client for ACME Corp"
  • "Log an expense for project 'Website Redesign'"
  • "Generate an invoice for hours worked this week"

Complete Code

Here's the complete code to get you started with Harvest and Claude Code:

import 'dotenv/config';
import { Composio } from '@composio/core';

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 composioClient = new Composio({ apiKey: COMPOSIO_API_KEY });

const composioSession = await composioClient.create(USER_ID, {
  toolkits: ['harvest'],
});

const composioMcpUrl = composioSession?.mcp.url;

console.log(`MCP URL: ${composioMcpUrl}`);
console.log(`\nUse this command to add to Claude Code:`);
console.log(`claude mcp add --transport http harvest-composio "${composioMcpUrl}" --headers "X-API-Key:${COMPOSIO_API_KEY}"`);

Conclusion

You've successfully integrated Harvest with Claude Code using Composio's MCP server. Now you can interact with Harvest directly from your terminal using natural language commands.

Key features of this setup:

  • Terminal-native experience without switching contexts
  • Natural language commands for Harvest operations
  • Secure authentication through Composio's managed MCP
  • Tool Router for dynamic tool discovery and execution

Next steps:

  • Try asking Claude Code to perform various Harvest operations
  • Add more toolkits to your Tool Router session for multi-app workflows
  • Integrate this setup into your development workflow for increased productivity

You can extend this by adding more toolkits, implementing custom workflows, or building automation scripts that leverage Claude Code's capabilities.

TOOLS

Supported Tools

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

Create Client

Tool to create a new client.

Create Client Contact

Tool to create a new client contact.

Create Estimate

Tool to create a new estimate.

Create Estimate Item Category

Tool to create a new estimate item category in Harvest.

Create Estimate Message

Tool to create a new message for an estimate.

Create Expense

Tool to create a new expense entry.

Create Invoice

Tool to create a new invoice.

Create Invoice Item Category

Tool to create a new invoice item category.

Create Invoice Message

Creates a new message for an invoice in Harvest.

Create Invoice Payment

Tool to create a new payment on an invoice.

Create Project

Create a new project in Harvest.

Create Task

Creates a new task in Harvest.

Create Time Entry

Tool to create a new time entry.

Create User

Creates a new user in Harvest and sends an invitation email to the specified address.

Delete Client

Tool to delete a client.

Delete Client Contact

Permanently deletes a client contact from Harvest.

Delete Estimate

Tool to delete an estimate.

Delete Estimate Message

Tool to delete an estimate message.

Delete Invoice

Delete an invoice from Harvest.

Delete Invoice Item Category

Tool to delete an invoice item category from Harvest.

Delete Invoice Message

Tool to delete a message from an invoice.

Delete Invoice Payment

Tool to delete an invoice payment.

Delete Project

Tool to delete a project.

Delete Task

Tool to delete a task.

Delete Time Entry

Tool to delete a time entry.

Delete User

Tool to delete a user.

Get Client

Retrieves a specific client by ID from Harvest.

Get Company Info

Retrieves detailed information about the company associated with the authenticated Harvest account.

Get Estimate

Tool to retrieve a specific estimate by ID.

Get Invoice

Tool to retrieve a specific invoice by ID.

Get Project

Tool to retrieve a specific Harvest project by ID.

Get Task

Tool to retrieve a specific task by ID.

Get Time Entry

Tool to retrieve a single time entry by ID.

Get User

Tool to retrieve a specific user by ID.

List Client Contacts

Tool to list client contacts.

List Clients

Tool to list clients.

List Estimate Messages

Lists all messages associated with a specific estimate in Harvest.

List Expense Categories

Tool to list expense categories.

List Invoice Item Categories

Tool to retrieve invoice item categories.

List Invoice Messages

Tool to list messages associated with a given invoice.

List Invoice Payments

List all payments recorded for a specific invoice.

List Invoices

Tool to list invoices.

List projects

Tool to list projects.

List Tasks

Tool to list tasks.

List Time Entries

Tool to retrieve a list of time entries.

List Users

Tool to list users.

Update Client

Tool to update an existing client.

Update Client Contact

Tool to update a client contact.

Update Company Info

Updates company time tracking settings in Harvest.

Update Estimate

Tool to update an existing estimate.

Update Estimate Item Category

Updates an existing estimate item category's name in Harvest.

Update Expense

Tool to update an existing expense.

Update Invoice

Tool to update an existing invoice.

Update Project

Tool to update an existing project.

Update Task

Tool to update an existing task.

Update Time Entry

Tool to update an existing time entry.

Update User

Tool to update an existing user.

FAQ

Frequently asked questions

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

Yes, you can. Claude Code 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 Harvest tools.

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

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