How to build an app ChatGPT can use.

The shortest path is not to build another chatbot. The shortest path is to expose your app’s useful actions as tools that ChatGPT can call with permission.

The simple model

1. Choose the actions your app should expose.
2. Describe each action with a name, schema, and permission scope.
3. Connect those actions to your existing API.
4. Publish the app to a gateway that ChatGPT can reach through MCP.
5. Let users install and approve the app.

What the code should feel like

import { geostack } from "@geostack/sdk";

const app = geostack.app("Booking Demo");

app.tool("search_hotels", async ({ city }) => {
  return searchHotels(city);
});

export default app;

What GEOstack handles

GEOstack is designed to handle the infrastructure around that simple developer surface: MCP transport, tool discovery, workspace installs, OAuth connection, scoped visas, tool routing, and audit logs.

What ChatGPT sees

ChatGPT should not see your whole backend. It should see a clean list of approved tools for the current user workspace. If the user did not install the app or grant the scope, the tool should not be available.

The goal

A developer should be able to go from API to AI-usable app without learning every AI client’s plugin system. Publish once, connect everywhere.