The short answer
canmore.create_textdoc creates a ChatGPT Canvas document beside the chat. Use Calculator Tools when that document should be a public app you own. Connect MCP or an official custom GPT. The host call is webappCreate.
Related names in the same public prompt copy are canmore.update_textdoc and canmore.comment_textdoc. They edit the Canvas file. They do not create a calculator.tools URL.
What this call does
Public copies of an October 2024 ChatGPT Canvas prompt describe a tool namespace canmore. canmore.create_textdoc takes a name, a type, and content. The type can be a document, a code file, or webview for HTML shown to the user.
The prompt says HTML, JavaScript, and CSS for a webview go in a single file. canmore.update_textdoc rewrites that file. canmore.comment_textdoc leaves comments on it.
The file lives in ChatGPT. Sharing still depends on ChatGPT's product. See ChatGPT Canvas.
What Calculator Tools does
Calculator Tools hosts the page on your account. Visitors open a calculator.tools URL. They do not need the Canvas thread.
Files live in one directory. Extra static files are normal: CSS, JavaScript, JSON, SVG, and similar types next to index.html.
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
Use Canvas while you draft. Publish when the page should leave the chat.
In ChatGPT, use an official custom GPT or add https://api.calculator.tools/mcp/. Sign in with Google. Click Approve.
Call canmore_create_textdoc on this server (the same inputs as canmore.create_textdoc: name, type, and content). The server calls webappCreate and stores the body as index.html. A document that is not HTML is wrapped so it still opens as a page.
From the browser, skip Canvas and open Create.
Limits
Calculator Tools does not run canmore.create_textdoc. It does not store the Canvas comment thread.
A webview that depends on ChatGPT's iframe rules is not the hosted app. Rebuild the page as static files. If you need a server, this host is the wrong target.
Check the math before you share the link.
Next step
Open Create, use a custom GPT, or connect MCP. The first 3 apps are free.
Sources
Ready to publish a public app you own?
Calculator Tools