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Integration · Accounting

Connect Claude & ChatGPT to Harpoon

Ask your AI to log three hours on a project, draft an invoice for a client or show which invoices are still open in Harpoon. It can create and update clients, contacts and projects, record expenses and create estimates. Payments received on invoices and time entries can be looked up without clicking through the app.

Connect Harpoon free

Free plan, no credit card. Takes about a minute.

Try asking

  • “Log 3 hours on the Acme website project for today: homepage design.”

    The AI finds the project and a task, then creates a time entry with date, hours and description.

  • “Create an invoice for Holm Logistics for 12 hours of consulting at 950 an hour.”

    It gets the next invoice number and creates the invoice with the line item in Harpoon. It does not email it.

  • “Which invoices are still unpaid this year?”

    It searches invoices by year and status and lists them with client, total and due date.

What your AI can do

Time and projects

Search, create and update projects with budgets, dates and task rates, and log, edit or delete time entries against projects and tasks.

Invoices and estimates

Search and read invoices and estimates, create them with the next free document number, update invoices and list payments received.

Clients and expenses

Create and update clients and contacts, record and update expenses by category, and add notes to clients or projects.

  • “Make an estimate for Nordic Foods: new webshop, 40 hours.”

    It gets the next estimate number and creates the estimate with client, subject and line items.

  • “Record a 450 expense from Adobe for software on the Acme project.”

    It finds the category and project and records the expense with date, amount and vendor.

  • “Delete my time entry from yesterday on the internal project.”

    It finds the entry and deletes it. Deleting a time entry is permanent.

30 tools for Harpoon

These tools are switched on when you connect. You can switch any of them off, or require your approval before it runs.

  • add_noteChanges dataAdd a note with body to a record, identified by notable_type and notable_id (e.g. a client or project).
  • create_clientChanges dataCreate a client with client_name, plus optional address, contacts, language and tax details.
  • create_contactChanges dataAdd a contact person to a client with client_id, first_name and email (optional last_name, phone).
  • create_estimateChanges dataCreate an estimate with issue_date and document_id, plus client_id, subject, line_items, due_date and project_id.
  • create_expenseChanges dataRecord an expense with date, amount and vendor, plus optional client, project, category and description.
  • create_invoiceChanges dataCreate an invoice with client_id, issue_date and document_id, plus line_items, due_date, discount, shipping and project_id. It is saved in Harpoon; this does not email it.
  • create_projectChanges dataCreate a project with project_name, client_id and type, plus optional budget, start/end dates, status and custom task rates.
  • create_time_entryChanges dataLog time with date and hours (optional seconds, project_id, task_id, description, timer_status).
  • delete_time_entryDeletesPermanently delete a time entry by page_id.
  • get_clientGet one client by customer_id, with address, contacts, language and tax details.
  • get_estimateGet one estimate by quote_id, with line items and totals.
  • get_invoiceGet one invoice by invoice_id, with line items, totals, due date and status.
  • get_next_estimate_numberGet the next free estimate document number to use as document_id when creating an estimate.
  • get_next_invoice_numberGet the next free invoice document number to use as document_id when creating an invoice.
  • get_projectGet one project by project_id, with client, budget, dates and status.
  • list_clientsList all clients, with their IDs.
  • list_contactsList client contacts, optionally filtered by team_id.
  • list_expense_categoriesList expense categories with their IDs.
  • list_paymentsList payments received on invoices.
  • list_tasksList the tasks that time can be logged against, with their IDs.
  • list_time_entriesList time entries, filtered by clients, projects, tasks, status or date range. Paginated.
  • search_estimatesSearch estimates by search text, client_id, year, projects or status.
  • search_expensesSearch expenses by date range, clients, projects, categories or status.
  • search_invoicesSearch invoices by search text, client_id, year, projects or statuses. Paginated. Use to find an invoice's ID.
  • search_projectsSearch projects by search text, client_id, status or type, with sorting and paging. Use to find a project's ID.
  • update_clientChanges dataUpdate a client's name, address, contacts, language or tax details by customer_id.
  • update_expenseChanges dataUpdate an expense by expense_id: date, amount, vendor, category, project or description.
  • update_invoiceChanges dataUpdate an invoice by invoice_id: line items, dates, status, discount or shipping.
  • update_projectChanges dataUpdate a project by project_id: name, budget, dates, status or task rates.
  • update_time_entryChanges dataUpdate a time entry by page_id: date, hours, project, task, description, timer or billed status.

Set up in three steps

  1. 1

    Pick the app

    Create a free PipMCP account and choose Harpoon from the app list.

  2. 2

    Paste your key

    Paste a Harpoon personal access token. In Harpoon open your Account's API page, create a personal access token and paste it here without the word Bearer.

  3. 3

    Add the link to your AI

    You get a personal MCP link. Add it to Claude, ChatGPT or Cursor:

    1. Click your name, then Settings › Connectors › Add custom connector.
    2. Paste your link as the Remote MCP server URL.
    3. Switch it on from the + menu in a chat.

Questions

What can the AI do in Harpoon?

The AI can read and search clients, contacts, projects, tasks, time entries, invoices, estimates, expenses, expense categories and payments. It can create and update clients, projects, time entries, invoices and expenses, create contacts and estimates, add notes and delete time entries.

Does the AI see my Harpoon access token?

No. Your Harpoon credentials are encrypted at rest and never shown to the AI. After you save them, they are not shown again, not even to you. The AI only sees the results of the tools it calls.

Can I control what the AI is allowed to do?

Yes. You choose which tools are switched on, so you can start read-only. Deleting a time entry is permanent and can require your approval before it runs, as can creating invoices or changing projects. Every tool call is logged.

Does it work with ChatGPT?

Yes. In ChatGPT go to Settings › Apps & Connectors › Advanced and turn on Developer mode, then add your PipMCP link. Developer mode needs a paid ChatGPT plan: Plus, Pro, Business or Enterprise. The same link also works in Claude (Settings › Connectors › Add custom connector), Cursor and other MCP clients.

What does it cost?

PipMCP has a free plan with no credit card required. Paid plans bill per completed task. You also need your own Harpoon account.

Can the AI send invoices to my clients?

No. The AI can create and update invoices and estimates, but they are saved in Harpoon only. Creating an invoice does not email it, so you review and send it from Harpoon yourself.

Let your AI work in Harpoon today.

Start free. Your key stays encrypted, and you decide what the AI may do.

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PipMCP is not affiliated with Harpoon. Product names are trademarks of their owners.