The short answer
file_gen:generate_pdf is a namespaced tool string. A public post reported it as a Google Search query. Use Calculator Tools when the real job is a public calculator or tool, not a PDF file. MCP calls webappCreate and returns a calculator.tools URL.
The string sits next to the API name file_gen. This host does not generate the office file that name describes.
What this call does
A public Gemini prompt copy names an API file_gen. The summary says it creates or exports downloadable files such as docx, xlsx, csv, pdf, md, tex, zip, and txt. In that copy the function list is empty. The copy does not print file_gen:generate_pdf.
Other tools in the same copy use namespace:function, for example google:search and retriever:expand_tools. file_gen:generate_pdf matches that shape. Treat the full string as a reported query, not as a published method spec.
The call, when it works inside Gemini, downloads a file. It does not open an account on this site.
What Calculator Tools does
Calculator Tools hosts a static web app. A mortgage calculator, a unit converter, or a scoreboard lives as HTML, CSS, and JavaScript.
Files live in one directory. You stay the owner. People open the page without Gemini.
Free accounts can publish 3 apps. Pro ($5.99/month) raises the limit to 25.
How to use MCP for this job
If you need the PDF itself, use the product that exports files. This page does not map file_gen onto a PDF endpoint.
If the PDF was only a way to share a calculator, publish the calculator.
Add https://api.calculator.tools/mcp/ in Cursor, Claude, or ChatGPT. Sign in with Google. Click Approve. Ask for the hosted app. The assistant calls webappCreate, then webappfileCreate for index.html and the other static files.
Or open Create and describe the calculator there.
Limits
Calculator Tools does not implement file_gen or file_gen:generate_pdf. It does not return a PDF download.
It also does not replace a spreadsheet. For a page people can use in the browser, publish here. Check the formulas.
Next step
Open Create or connect MCP. The first 3 apps are free.
Sources
Ready to publish a public app you own?
Calculator Tools