MCP Server
MCP overview
Connect Claude, ChatGPT, Grok, Gemini CLI or any MCP client to Free Invoice Automation with a browser sign-in and no AI key.
The Model Context Protocol (MCP) is an open standard that lets an AI assistant use tools from other services. Our hosted MCP server gives your assistant tools to create invoices and estimates, look up clients, record payments, check what is overdue and send documents, all on your own account and under your own permissions. You sign in through your browser; there is nothing to install for remote clients and no AI key to provide.
Server details
| Server URL | https://mcp.freeinvoiceautomation.com/mcp |
| Transport | Streamable HTTP |
| Server name | freeinvoiceautomation-mcp |
| Sign-in | OAuth 2.0 in your browser, or an API key |
| Local option | freeinvoiceautomation-mcp stdio client on npm, with an API key |
| Tools | 28 in total; see the tool reference |
| Cost | Free on every plan. MCP calls never use AI credits |
Set up your client
Connect your AI assistant
Sign in via browser. No AI key needed.
Add a custom connector in Claude, or run the command below in Claude Code.
Open Claude connectorsclaude mcp add --transport http freeinvoiceautomation https://mcp.freeinvoiceautomation.com/mcpThen enter /mcp in Claude Code and confirm freeinvoiceautomation is connected.
Using another MCP client? Point it at:
https://mcp.freeinvoiceautomation.com/mcpStep-by-step guides for each client:
Claude
Claude apps and Claude Code.
ChatGPT
A custom connector in developer mode.
Grok
A custom connector, or the xAI API.
Gemini CLI
settings.json and /mcp.
Other clients
Any streamable HTTP client, or the local stdio client.
Authentication
OAuth, API keys, scopes and modes.
How it works
Your assistant connects
You add the server URL to your client. The first time it connects, the client opens our sign-in page in your browser.
You sign in and approve
You sign in to Free Invoice Automation, pick the account to connect, and approve the scopes (what the assistant may do) and the mode: draft_only, the default, or auto_send. The consent screen shows the name of the client asking for access.
Your assistant calls tools
When you ask for something, the assistant picks tools such as list_clients and create_invoice and calls them. Each call is checked against the token's scopes and your role's current permissions, runs the same action as the matching API endpoint, and is written to the audit log.
You confirm anything that matters
New documents are drafts. Sending needs confirm: true unless the token is auto_send, and destructive tools such as void_document always need confirm: true. Without it the tool returns a preview so the assistant can show you what would happen.
What your assistant can do
At launch on 1 January 2027 the server has 18 tools; ten more arrive with their features during 2027.
| Area | Tools at launch | Later |
|---|---|---|
| Documents | create_invoice, update_invoice, create_estimate, list_documents, get_document, list_overdue, render_pdf | set_payment_schedule (Jan), create_contract (Mar) |
| Sending | preview_send, send_document | send_reminder (Jan) |
| Corrections | void_document, create_credit_note | |
| Clients and items | list_clients, upsert_client, list_items, upsert_item | |
| Payments | record_payment, get_payment_status | |
| Reports | get_aged_receivables, get_report (Jan), get_ledger_report (Jun to Jul) | |
| Time and expenses | log_time, list_unbilled_time, invoice_unbilled, record_expense (Apr) | |
| No sign-in | generate_pdf |
Each tool carries annotations from its definition: a title, readOnlyHint or destructiveHint, idempotentHint (sends are idempotent, so a retried send never emails twice), and a link to its docs page. Clients use these to decide when to ask you before running a tool.
Some actions exist in the API but are not MCP tools, for example deleting a client, refunding a payment or managing team members. Your assistant cannot do these through MCP. Use the web app or the API for them.
Example conversation
Who owes me money right now?The assistant calls list_overdue and summarises the overdue invoices by client.
Send Acme a copy of invoice INV-2027-0004 again, and create a new draft for 3 days of consulting at 400 USD a day.The assistant calls preview_send for the existing invoice and shows you the email, then calls create_invoice for the new draft. It asks before calling send_document with confirm: true, because your token is draft_only.
Requirements and limits
- An account. Any plan. The MCP server is free, and the tools work the same on Free and Team.
- Permissions. A tool works only if your role has its permission key, for example
documents.createforcreate_invoice. A Viewer can read but not write. - One account per connection. A token is bound to one user and one account. If you belong to several accounts, connect once per account.
- Rate limits. Calls are rate-limited per token, like API keys. Over the limit you get
rate_limitedwith aRetry-Aftervalue. See Rate limits. - Fair use on Free. API and MCP calls count toward the Free plan's monthly fair-use limits, which exist only to stop abuse.
The MCP server and the AI agent
The MCP server and the AI invoice agent call the same actions, but the AI runs in different places:
- With MCP, your own assistant (Claude, ChatGPT and so on) does the thinking. Our server only runs the tools it calls. No credits are used.
- With the agent, the thinking happens inside Free Invoice Automation, on our AI key or your own. It uses credits unless you connect your own key.