Quick start

You write one file. The running app finds it, and every AI step can use the tool in it.

1. Find the plugins folder

You run	The folder
engenty wizards on your computer (`wizards`)	`~/.engenty/wizards/plugins`
A checkout (`pnpm dev`)	The folders that `PLUGINS_DIR` names in `.env.local`, for example `PLUGINS_DIR=../my-plugins`. A relative path starts at the checkout’s root

Start the app. It creates the folder if it is missing and watches it while it runs.

2. Write the plugin

Save this as workdays.ts in the plugins folder:

import { definePlugin } from "@engenty/wizards/plugin";
import { z } from "zod";

export default definePlugin((wizards) => {
  wizards.server.registerTool({
    name: "count",
    title: "Working days",
    description:
      "Counts the working days (Monday to Friday) from one date to another, both included.",
    inputSchema: z.object({
      from: z.string().describe("First day, YYYY-MM-DD"),
      to: z.string().describe("Last day, YYYY-MM-DD"),
    }),
    execute: async ({ from, to }, step) => {
      await step.emit("Counting working days …");
      const last = new Date(`${to}T00:00:00Z`);
      let workingDays = 0;
      for (let day = new Date(`${from}T00:00:00Z`); day <= last; day.setUTCDate(day.getUTCDate() + 1)) {
        if (day.getUTCDay() % 6 !== 0) {
          workingDays += 1;
        }
      }
      return { from, to, workingDays };
    },
  });
});

The file’s name is the plugin’s id: workdays.
The tool’s full id is workdays.count.
@engenty/wizards/plugin and zod come from the app, so you don’t install anything.

3. See it

The app loaded the file the moment you saved it.

Settings → Plugins lists workdays, with workdays.count under “Tools for steps”.
In the editor, open an AI step: workdays.count is in its list of tools, beside web_search and the other built-in ones. The line below the list says “workdays.count = Working days”.
In the editor’s chat, ask for it: “Add a step that counts the working days between the two dates.” The assistant knows the tool from its description.

In a wizard’s definition the step lists the tool by its full id:

{
  "id": "countDays",
  "type": "agent",
  "title": "Count the working days",
  "instructions": "Count the working days from {{start}} to {{end}}.",
  "tools": ["workdays.count"],
  "model": "standard",
  "output": { "format": "json", "fields": [{ "id": "days", "kind": "number", "description": "Working days" }] }
}

4. Change it

Edit the file and save. The plugin loads again, and the next step that runs uses the new code.

If the file has an error, Settings → Plugins says “The server part didn’t load. Check the plugin and reload” with the reason. Fix the file and save it again.

To	Read
Keep data	Tables
React when a run ends	Events
Show a page in the studio	The studio half
Give the plugin a name, a version and more than one file	Files and manifest

1. Find the plugins folder

2. Write the plugin

3. See it

4. Change it

Next

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