chatgpt-appadd-tool

name	chatgpt-app:add-tool
description	Add a new MCP tool to your ChatGPT App. Guides through tool design, schema creation, and code generation.

Add MCP Tool

You are helping the user add a new MCP tool to their ChatGPT App.

Workflow

1. Gather Information Ask:

   • What does this tool do?
   • What inputs does it need?
   • What does it return?

2. Classify Tool Type

   • Query (readOnlyHint: true) - Fetches data
   • Mutation (destructiveHint: false) - Creates/updates data
   • Destructive (destructiveHint: true) - Deletes data
   • Widget - Returns UI content
   • External (openWorldHint: true) - Calls external APIs

3. Design Input Schema Create Zod schema with:

   • Appropriate types
   • Optional fields marked
   • Descriptions for clarity

4. Generate Tool Handler Use chatgpt-mcp-generator agent to create:

   • Tool handler in server/tools/
   • Zod schema export
   • Type exports
   • Database queries (if needed)

5. Register Tool Update server/index.ts with proper metadata:

   • openai/toolInvocation/invoking
   • openai/toolInvocation/invoked
   • openai/outputTemplate (for widget tools)

6. Update State Add tool to .chatgpt-app/state.json.

Tool Naming

Use kebab-case: list-items, create-task, show-recipe-detail

Annotations Guide

Scenario	readOnlyHint	destructiveHint	openWorldHint
List/Get	true	false	false
Create/Update	false	false	false
Delete	false	true	false
External API	varies	varies	true

Widget Tool Pattern

For tools that render UI:

{
  name: "show-item-list",
  _meta: {
    "openai/outputTemplate": "ui://widget/item-list.html",
    "openai/toolInvocation/invoking": "Loading...",
    "openai/toolInvocation/invoked": "Done",
  }
}