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Summary
Invoice123 (Saskaita123), invoicing for Lithuania and Latvia, read-only: sales invoices with payments, payment links and PDFs, purchases, clients, products, projects, waybills, VAT rates, series and bank accounts.
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Example prompts for Invoice123
Click any prompt to copy it. Paste into Claude, ChatGPT, Cursor, Gemini, Copilot or OpenClaw to run it against this connector.
Claude is AI and can make mistakes. Please double-check responses.
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Invoice123 + ChatGPT
Invoice123 (Saskaita123), invoicing for Lithuania and Latvia, read-only: sales invoices with payments, payment links and PDFs, purchases, clients, products, projects, waybills, VAT rates, series and bank accounts.
Prerequisites
See the full setup instructions baked into the connector (visible in the in-app store when you select the connector). The required environment variables for this connector are:
INVOICE123_API_TOKEN
Step 1 — Get credentials
Setting up takes about 2 minutes. You need an Invoice123 account (Saskaita123 in Lithuania) where you can install integrations.
- In Invoice123 open the account menu (top right), then Integrations (puzzle icon) or Account settings > Integrations, and install the API integration.
- Click Generate your API key, name it and tick the permissions the AI may use: at least
invoice:index, plusexpense:index,client:index,product:index,project:indexandwaybills:indexfor those areas. The invoice PDF checksinvoice:store, and the offer PDFcommercial:store. - Paste only the key into
INVOICE123_API_TOKEN, without the word Bearer, spaces or quotes. The connector sends it asAuthorization: Bearer. - Install the connector and run
invoice123_get_companyto check the token.
What it reads: sales invoices with client, line items, VAT, totals, currency, payments and paid flag; the payments of one invoice, that is how and when it was paid (transfer, cash, card, cash register receipt); the online payment link of an invoice when the company has Montonio or Paysera enabled; invoice and commercial offer PDFs in Lithuanian, English or Latvian; purchase invoices (expenses) with expense types, VAT and payments; clients (customers and suppliers); the product catalog with prices and stock per warehouse; projects with budget; waybills; and the reference data: document series, VAT rates for sales and purchases, bank accounts, units, activities, cash registers and e-mail templates.
How the AI works with it: when it needs ids it reads the reference data first, in one call with invoice123_get_invoice_data (activities, series, banks, units, VAT rates and warehouses) or one list at a time. For open items it filters invoice123_list_invoices by status unpaid or late, for a period by range, and for one customer by client_id; invoice123_list_invoice_payments then shows how an invoice was settled.
Read-only: all 21 tools only read. Nothing is issued, sent or changed in Invoice123, so there is nothing to confirm and no tool is switched off at install.
Paging, dates and amounts: lists return data.result and data.pagination (current_page, last_page, total); the AI passes page (from 1) and limit (default 20) and stops at last_page. A date range is two YYYY-MM-DD dates joined by a comma. Amounts are strings in the invoice currency, usually EUR.
Limits: 60 requests per minute on the Standard plan, 1,000 per hour on Business. Above that Invoice123 answers 429.
Common errors: 401 means a wrong or deleted token. 403 means the token lacks the permission named in the tool description; purchases, waybills and offers also need their module enabled in the account.
Step 2 — Install the adapter
curl -fsSL https://raw.githubusercontent.com/HelpCode-ai/anythingmcp/main/docker-compose.quickstart.yml -o docker-compose.yml
printf 'JWT_SECRET=%s\nENCRYPTION_KEY=%s\n' "$(openssl rand -hex 32)" "$(openssl rand -hex 32)" > .env
docker compose up -d
Step 3 — Add the connector in ChatGPT
Your server URL: in AnythingMCP, open MCP Servers → the server this connector is on, and copy its URL (
https://cloud.anythingmcp.com/mcp/…). Use it wherever this guide showsYOUR_SERVER_ID.
ChatGPT adds MCP servers as plugins on its Plugins page, on the web and on paid plans. Developer mode is no longer needed. In a Business workspace only admins and owners can add one; in Enterprise and Edu an admin can grant the Create plugins with MCPs permission.
- Go to chatgpt.com/plugins, click Add, then Add custom MCP server.
- Enter a name, e.g. Name:
Invoice123. - Under Connection, enter the Server URL
https://cloud.anythingmcp.com/mcp/YOUR_SERVER_IDand keep Authentication on OAuth. - Select I understand and want to continue, then Create as a plugin. When ChatGPT asks, sign in to AnythingMCP and allow access.
- Install the new plugin from your personal plugins, then type @ in a chat and pick it.
Available tools
| Tool | What it does |
|---|---|
invoice123_get_company | Get the company profile behind the API token (currently whether the company is VAT registered) |
invoice123_list_invoices | List sales invoices with client, line items, VAT, totals, currency, payments and paid flag, 20 per page by default |
invoice123_list_invoice_payments | List the payments registered for one invoice: type (transfer, cash, refund, other), cash document type and receipt number, amount, date and… |
invoice123_download_invoice_pdf | Download the PDF of an invoice in Lithuanian, English or Latvian; the file is handed over as an attachment |
invoice123_get_invoice_payment_link | Get the online payment link of an invoice, when the company has a payment provider (Montonio or Paysera) enabled |
invoice123_list_invoice_vat_rates | List the VAT rates available on sales invoices: id, VAT code (e.g |
invoice123_get_invoice_data | Get in one call the reference data used on invoices: activities, document series, bank accounts, units, VAT rates and warehouses, with… |
invoice123_list_purchases | List purchase invoices (expenses) with supplier, line items with expense type, VAT, totals, payments and paid flag |
invoice123_list_purchase_vat_rates | List the VAT rates available on purchase invoices: id, VAT code, tariff in percent and reverse-charge article |
invoice123_list_purchase_types | List the expense types (purchase categories) that purchase line items can carry, with their ids |
invoice123_download_commercial_offer_pdf | Download the PDF of a commercial offer (quote) in Lithuanian, English or Latvian; the file is handed over as an attachment |
invoice123_list_clients | List clients (customers and suppliers): id, name, company or personal code, client code, VAT code, address and country |
invoice123_list_products | List the product catalog: id, name, code, price, description, prime cost, type, weight and stock per warehouse |
invoice123_list_projects | List projects with number, description, start and end dates and budget |
invoice123_list_waybills | List waybills (delivery notes) with type, series, receiver, carrier, load and delivery dates and the linked invoice series, at most 50 per… |
invoice123_list_bank_accounts | List the company bank accounts (IBAN, bank name, code, SWIFT, default flag) that invoices show for payment |
invoice123_list_series | List document series (numbering ranges) with id, title and type: simple, advance, credit invoices, and the cash documents kpo, ppk, kio |
invoice123_list_cash_registers | List the company cash registers with register number, last receipt number and receipt pattern |
invoice123_list_units | List the measurement units (pcs, hours, kg...) with their ids, as used on invoice lines |
invoice123_list_activities | List the business activities (for individual activity accounts) with their ids, used to filter invoices and purchases |
invoice123_list_email_templates | List the e-mail templates the company uses to send invoices, with their ids and names |
Example prompts
- "Which invoices are late, for how much, and which clients are they for?"
- "How and when was the last invoice to UAB Pavyzdys paid?"
- "List this month's purchase invoices by expense type with their VAT."
- "Give me the online payment link for the open invoice of UAB Pavyzdys."
- "Download the PDF of our latest invoice in English."
FAQ
Does the free ChatGPT plan work with custom MCP servers? OpenAI documents custom MCP servers for paid plans only; the Free plan is not on its list.
Next steps
- Connector landing page
- Connect to Claude
- Connect to Cursor
- Connect to Gemini
- Connect to Meta Muse
- Connect to Microsoft Copilot
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