1. Pick one workflow

The easiest first app is not a whole product. It is one narrow workflow with a clear before and after: search records, summarize a project, create a task, update a design, or query a database.

Write the user promise in one sentence before you write code. If the promise needs more than one sentence, split it into smaller tools.

  • Good first workflow: Search open support tickets and summarize the top blockers.
  • Risky first workflow: Give the model full access to every customer system and hope it chooses safely.
  • Best first milestone: One read-only tool, one happy path, one useful result shape.

2. Define the tool contract

An MCP tool should have a name the model can understand, a concise description, and a typed input schema. The description is part of the product surface because the model uses it to decide when the tool is relevant.

{
  "name": "search_projects",
  "description": "Search active projects by customer, owner, status, or keyword.",
  "inputSchema": {
    "type": "object",
    "properties": {
      "query": { "type": "string" },
      "status": { "type": "string", "enum": ["active", "blocked", "done"] }
    },
    "required": ["query"]
  }
}

3. Build the server

Use an official MCP SDK when possible. The official MCP docs list SDKs for TypeScript, Python, C#, Go, Java, Rust, and other languages.

For a ChatGPT app, OpenAI's Apps SDK flow expects an MCP server and can render an optional iframe UI. Start locally, then deploy the server over an HTTP transport when you are ready to connect from hosted clients.

  1. Create the MCP server project.
  2. Register your first read-only tool.
  3. Return structured content that the model and UI can both use.
  4. Add auth only after the tool shape is stable.
  5. Log tool calls and errors without storing unnecessary user data.

4. Add UI only where it helps

A UI is useful when users need to inspect structured output, compare options, or make a precise selection. It is not required for every MCP app.

For ChatGPT apps, the UI runs in an iframe and communicates with the host through the MCP Apps bridge. Keep the UI focused: one result view, one clear action, and no hidden surprises.

5. Prepare for review and discovery

Your listing should explain what the app can read, what it can write, which platforms it supports, what auth it uses, and which examples prove the workflow.

Good SEO and good review materials overlap: precise title, plain-language description, screenshots or previews, privacy links, support links, and honest capability labels.

  • Add homepage, privacy, terms, and support URLs.
  • List every platform surface separately: ChatGPT app, Claude connector, Claude Code, or another host.
  • Include example prompts that show real use, not marketing claims.
  • Prefer least-privilege OAuth scopes and read-only first releases.