useRegisterTool

sunpeak API

Overview

Returns a function to register tools that the host (or LLM) can call. Uses Standard Schema (Zod, ArkType, Valibot) for input/output validation. The returned handle supports enable(), disable(), remove(), and update(). For simpler static tool registration, see useAppTools. useRegisterTool provides lower-level control with dynamic registration and Standard Schema support. The underlying MCP Apps registry sends notifications/tools/list_changed automatically when you register, update, enable, disable, or remove a tool and the View declared tools.listChanged.

Import

import { useRegisterTool } from 'sunpeak';

Signature

function useRegisterTool(): (
  name: string,
  config: RegisterToolConfig,
  cb: AppToolCallback
) => RegisteredAppTool | undefined

RegisterToolConfig

string

Human-readable title for the tool.

string

Description of what the tool does.

StandardSchemaV1

Input validation schema (Zod, ArkType, Valibot, etc.).

StandardSchemaV1

Output validation schema.

ToolAnnotations

Tool annotations (readOnly, destructive, idempotent hints).

Returns

(name, config, cb) => RegisteredAppTool | undefined

Function to register a tool. Returns undefined if app is not connected.

RegisteredAppTool

() => void

Enable the tool.

() => void

Disable the tool.

() => void

Remove the tool registration.

(updates) => void

Update the tool configuration.

Usage

import { useRegisterTool } from 'sunpeak';
import { useEffect } from 'react';

function SelectionTool({ selectedText }: { selectedText: string }) {
  const registerTool = useRegisterTool();

  useEffect(() => {
    const handle = registerTool(
      "get_selection",
      { description: "Get the user's current text selection" },
      () => ({
        content: [{ type: "text", text: selectedText }],
      })
    );
    if (handle) {
      return () => handle.remove();
    }
  }, [registerTool, selectedText]);

  return <div>Selection tool registered</div>;
}

Do not call useSendToolListChanged() after these registry operations. Use that lower-level hook only when you manage a custom onlisttools result.

Getting Started

CLI

Components

Functions

Hooks

Resources

Tools

Guides

useRegisterTool

Overview

Import

Signature

RegisterToolConfig

Returns

RegisteredAppTool

Usage

​Overview

​Import

​Signature

​RegisterToolConfig

​Returns

​RegisteredAppTool

​Usage

Overview

Import

Signature

RegisterToolConfig

Returns

RegisteredAppTool

Usage