The short answer
write_site_files writes files onto a Static.app site the agent already created. Use Calculator Tools when those files should be a calculator.tools app. MCP uses webappCreate for the app and webappfileCreate or webappfileUpdate for the file.
The Static.app publish step is create_site_from_archive. This page is the edit call.
What this call does
Static.app's MCP page lists write_site_files with read_site_file and delete_site_files. The documented example reads index.html, changes a line, and writes that file back. The address stays the same.
The server is https://mcp.static.app/sse. The request sends an API key. The write lands on a Static.app website, not on a Calculator Tools id.
What Calculator Tools does
Each app is a directory of static files on your account. The public URL stays put while you update a file.
Files live in one directory. An update replaces or adds one of those files. It does not zip the whole site.
You stay the owner. Free accounts can publish 3 apps. Pro ($5.99/month) raises the limit to 25.
How to use MCP for this job
Connect https://api.calculator.tools/mcp/. Sign in with Google. Click Approve.
Call the MCP tool write_site_files with webapp_id (or url) and files. The server writes those files on the app you own. A new app still starts with webappCreate. This call does not create a second app, and it does not call Static.app.
You can also edit after Create from the dashboard, or ask the assistant again through MCP.
Limits
Calculator Tools does not implement write_site_files. It does not list Static.app sites.
webappfileUpdate only changes an app you own here. It will not push a Vite bundle or a server function. Check the live page after the write.
Next step
Open Create or connect MCP. The first 3 apps are free.
Sources
Ready to publish a public app you own?
Calculator Tools