useCallTool

Actions hook from moonpeak.

import { useCallTool } from "moonpeak";

useCallTool(): (name: string, args?: object) => Promise<CallToolResult>

Call a tool on your MCP server through the host. Throws an Error with the tool's text when the result has isError: true (the result is on err.result).

Example

const callTool = useCallTool();

async function nextWeek() {
  const res = await callTool("show-moon", { date: "2026-12-01" });
  setState({ view: res.structuredContent, selected: 0 });
}

Notes

Tools marked visibility: ["app"] can be called here even though the model never sees them.

Works in

Every MCP Apps host: ChatGPT, Claude, VS Code, Goose and the moonpeak inspector.

See all hooks in Runtime APIs.