MCP Server or AI-Written Plugin: Which Way Fits?
GrandTotal offers two ways to put AI to work. Both use the same assistant, such as Claude, but in very different places. With the MCP server, the AI works directly in your data. With an AI-written plugin, the AI writes a program once, and that program then runs without it.
The MCP Server: The AI Works Alongside You
Through the Model Context Protocol, the AI assistant accesses your GrandTotal data while you talk to it. You ask a question or give an instruction, the AI reads revenue, clients and documents, and creates new records if you want. Every answer is produced at the moment you ask.
This fits when every task is different: a report that has never existed in this form, a quote built from a PDF request, a one-time import from an old FileMaker database. Photographer Simon Iannelli creates his shoot quotes this way, because no two quotes are alike. Data migration is another typical case: it happens once, and the AI maps the fields in conversation.
What you need: GrandTotal XL and a running AI assistant every time you use it. Without it, nothing happens. And the data, pseudonymized, goes to the AI service with every request.
The AI-Written Plugin: The AI Builds the Tool
With an AI-written plugin, the AI is only involved during development. You describe what the plugin should do, the assistant reads your tool's API documentation, tests the interface and writes the code. The result is an ordinary GrandTotal plugin. It runs in GrandTotal, without AI, without chat, the same way every time.
This fits everything that recurs: pulling logged hours from your time tracking tool every week, handing invoices to an archive system, connecting your CRM. The Integration Wizard generates the scaffold and the prompt for it. The post “The missing 5 %” is about the small, company-specific automations you can build this way.
What you need: GrandTotal L, XL & Classic, some patience in the Terminal once, and API credentials for development, which you rotate afterwards. Only interactive document templates, the plugins under File › New, require GrandTotal XL. In operation, no data flows to an AI service. The plugin only talks to GrandTotal and the connected tool.
That brings another advantage: such a plugin can be passed on. Colleagues, clients or other users of the same tool install it like any other GrandTotal plugin, without needing an AI assistant themselves. Many of the integrations GrandTotal ships with today came about exactly this way.
At a Glance
| MCP server | AI-written plugin | |
|---|---|---|
| Role of the AI | Takes part in every use | Writes the code once |
| Runs without AI | No | Yes |
| Edition | GrandTotal XL | GrandTotal L, XL & Classic, interactive document templates only XL |
| Result | Answer or record, new every time | Reusable plugin, always the same |
| Suited for | Questions, reports, one-offs, migration | Recurring workflows, integrations |
| Data flow in operation | Pseudonymized data to the AI service | Only between GrandTotal and your tool |
| Sharing | Not possible, the AI session is yours | Pass the plugin on to other users |
| Setup | Settings › MCP Server, copy token | Integration Wizard, Terminal, API access |
| Changes | Simply ask differently | Edit the plugin again with the AI |
Rule of Thumb
If you can state the task in one sentence and would phrase it differently again tomorrow, use the MCP server. If you run the task the same way every week or want to make it available to others, have a plugin written.
Which One When?
A report that never existed before
MCP server
A quote from a PDF request
MCP server
One-time data migration
MCP server
Import hours every week
AI-written plugin
Hand invoices to the archive
AI-written plugin
Share with colleagues
AI-written plugin
MCP server: Settings › MCP Server
AI-written plugin: Integration Wizard