Your AI Assistant Can Now Publish Real Apps on Calculator Tools
In my last post I talked about the new prompts and the latest Gemini models on Calculator Tools. At the very end I added a teaser about MCP and I figured I’d make follow-up post.
The big news: Calculator Tools now has agent tools. That means ChatGPT, Claude, Grok Bot, and even Cursor or VS Code can connect to your Calculator Tools account and actually build, publish, and edit live apps for you. Not a preview like some artifacts. A real page on calculator.tools with a fully working app already deployed.
Whoa! What Is the Calculator Tools MCP?
MCP stands for Model Context Protocol. It’s the standard way AI uses external tools and basically is a form of API. Calculator Tools MCP is those tools pointed at the Calculator Tools app host.
The idea is the same as it’s always been since I first launched Calculator Tools: you describe the app, the AI writes the HTML, CSS and JavaScript, and it’s instantly live. The difference is that now the AI can be the assistant you already use every day. And you are the creator of every app it publishes.
It’s also listed in the official MCP Registry as tools.calculator/mcp.
How Do I Connect It?
One URL. That’s it.
https://api.calculator.tools/mcp/
- Create a free Calculator Tools account if you don’t have one.
- Add the URL above as an MCP server in your assistant.
- Sign in with Google on Calculator Tools.
- Click Approve.
- Ask it to make an app. It should come back with a public calculator.tools link.
Cursor: open Cursor Settings, then MCP, add a new server and paste the URL. Cursor opens Calculator Tools so you can sign in and Approve.
Claude: add a custom connector and paste the same URL. Claude sends you to the Calculator Tools login page, you Approve, done.
ChatGPT: add the same URL as an MCP connection, sign in, Approve. The Calculator Tools custom GPTs still work too (the follow-up to the original GPT and the old ChatGPT plugin), and both save apps to the same account.
Some setups still want a token instead of a login. For those you can log in, open your dashboard, and copy your MCP code. Here’s the Cursor example from the MCP page:
{
"mcpServers": {
"calculator-tools": {
"url": "https://api.calculator.tools/mcp/",
"headers": {
"Authorization": "Bearer YOUR_MCP_CODE"
}
}
}
}
Treat that code like a password. Anyone who has it can publish apps on your account.
What Are All the Agent Tools?
Here’s every tool the assistant gets once you Approve. There are 11 of them, and they only work on your account and your apps.
1. webappCreate – Create an App
Makes a brand new hosted app from a title and a description and hands back the live public URL. The assistant then fills it in with the file tools below.
Try saying: “Create a Calculator Tools app called Pizza Party Splitter that splits a pizza order between friends.”
2. webappList – List Your Apps
Lists all the apps on your account, plus your membership status, so the assistant knows if you still have free apps left or need Pro.
Try saying: “List my Calculator Tools apps.”
3. webappRead – Read an App
Gets the details of one of your apps, including its files.
Try saying: “Open my Pizza Party Splitter app and tell me what it does.”
4. webappUpdate – Update an App’s Info
Changes the title or description of an app, and can add tags (up to 10).
Try saying: “Rename it to Pizza Math and tag it calculator, food and party.”
5. webappLogo – Set a Logo
Sets the app’s logo from a public image URL.
Try saying: “Use this image as the logo for my app: (link to your image).”
6. webappDelete – Delete an App
Permanently deletes an app you own. This one can’t be undone, so be sure!
Try saying: “Delete my old Test App 3.”
7. webappfileCreate – Create a File
Adds a file to an app. Think index.html, styles.css or app.js. It supports html, css, js, xml, svg, json, txt and csv files.
Try saying: “Write the index.html for Pizza Math with a big slice counter and a split button.”
8. webappfileRead – Read a File
Reads one file from an app, so the assistant can look at the current code before it changes anything.
Try saying: “Read the index.html of Pizza Math.”
9. webappfileUpdate – Update a File
Replaces a file’s content with a new version. This is how all the edits happen.
Try saying: “Add a tip calculator to the bottom of Pizza Math.”
10. webappfileList – List Files
Lists every file in an app.
Try saying: “What files are in my Pizza Math app?”
11. webappfileDelete – Delete a File
Removes one file from an app.
Try saying: “Delete the old styles.css from Pizza Math, everything is inline now.”
What If I Run Out of Free Apps?
Free accounts can publish a few apps and Pro gets you more (plus the stronger models on the website). If you hit the limit, the assistant gets back an upgrade_required message with a checkout link. You open the link and pay if you want to. The assistant can’t charge your card and never enters one.
Where Do the Apps Live?
Every app the assistant publishes is a normal Calculator Tools page under /app/. It’s not trapped in a chat. You can open it from your dashboard, share the link, or remix it later on the site. And because it’s still your app, you can always ask the assistant to come back and change it.
The app pages got a glow-up too. They’re full screen and immersive now, and they work a lot better on your phone, with Fullscreen and Share buttons that stay right where you need them. Here’s TinyTip on mobile:
Wait, How Is This Different From Artifacts or Canvas?
Great question, and there’s a whole new Info section for that. It has quick definitions for things like MCP, hosted apps, remix and ownership, plus comparison pages for Claude Artifacts, ChatGPT Canvas, v0, Bolt, Lovable, Replit and more.
The short version: an Artifact or Canvas is a preview inside your chat. Calculator Tools gives it a real public URL that you own. So you can iterate in Claude and then just say “publish this to Calculator Tools.”
Do I Still Have to Use an Assistant?
Nope! Everything still works right on the website. Chat with the AI on the create page, or start from a picture with Image to App and Screenshot to App. MCP doesn’t replace any of that. It’s the same publish step, just started from the assistant you already have open.
Did You Really Not Click the Link Yet?
Go grab the URL from the Calculator Tools MCP page, plug it into Cursor or Claude, and ask for the weirdest little app you can think of. Then send me the link!