add(coding-agent): add defineTool helper closes #2746

packages/coding-agent/examples/extensions/hello.ts

@@ -3,23 +3,24 @@
  */
 
 import { Type } from "@mariozechner/pi-ai";
-import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+import { defineTool, type ExtensionAPI } from "@mariozechner/pi-coding-agent";
+
+const helloTool = defineTool({
+	name: "hello",
+	label: "Hello",
+	description: "A simple greeting tool",
+	parameters: Type.Object({
+		name: Type.String({ description: "Name to greet" }),
+	}),
+
+	async execute(_toolCallId, params, _signal, _onUpdate, _ctx) {
+		return {
+			content: [{ type: "text", text: `Hello, ${params.name}!` }],
+			details: { greeted: params.name },
+		};
+	},
+});
 
 export default function (pi: ExtensionAPI) {
-	pi.registerTool({
-		name: "hello",
-		label: "Hello",
-		description: "A simple greeting tool",
-		parameters: Type.Object({
-			name: Type.String({ description: "Name to greet" }),
-		}),
-
-		async execute(_toolCallId, params, _signal, _onUpdate, _ctx) {
-			const { name } = params as { name: string };
-			return {
-				content: [{ type: "text", text: `Hello, ${name}!` }],
-				details: { greeted: name },
-			};
-		},
-	});
+	pi.registerTool(helloTool);
 }