tools.ts

import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import z from "zod";

// ============================================================================
// CONFIGURATION
// ============================================================================

const API_URL = process.env.API_ENDPOINT || "http://localhost:3001";
const _API_KEY = process.env.API_KEY || "";

// ============================================================================
// UTILITY FUNCTIONS
// ============================================================================

// Helper function for making API requests (supports GET, POST, body, etc.)
const _makeRequest = async <T>(
	api_url = API_URL,
	{
		method = "GET",
		headers = {},
		body = undefined,
	}: {
		method?: string;
		headers?: HeadersInit;
		body?: unknown;
	} = {},
): Promise<T | null> => {
	try {
		const fetchOptions: RequestInit = {
			method,
			headers,
		};
		if (body !== undefined) {
			fetchOptions.body =
				typeof body === "string" ? body : JSON.stringify(body);
			// Set JSON header if not already set
			if (
				typeof headers === "object" &&
				!(headers as Record<string, string>)["Content-Type"]
			) {
				(fetchOptions.headers as Record<string, string>)["Content-Type"] =
					"application/json";
			}
		}
		const response = await fetch(api_url, fetchOptions);

		if (!response.ok) {
			console.error(`Error: ${response.status} ${response.statusText}`);
			return null;
		}

		const data = await response.json();
		return data as T;
	} catch (error) {
		console.error("Fetch error:", error);
		return null;
	}
};

// ============================================================================
// TOOL DEFINITIONS
// ============================================================================

export const populateTools = (server: McpServer) => {
	// Demo tool: Say hello with optional name parameter
	server.tool(
		"say_hello", // first argument: tool name
		"Say hello to someone or everyone", // second argument: tool description
		{
			name: z
				.string()
				.optional()
				.describe("Name of the person to greet (optional)"),
		}, // third argument: tool parameters schema (using zod)
		async ({ name }) => {
			console.error(
				new Error("say_hello tool invoked", {
					cause: "for logging demonstration purposes",
				}),
			);
			console.log("say_hello tool invoked with name:", name);
			// fourth argument: tool implementation
			try {
				const greeting = name ? `Hello, ${name}!` : "Hello, world!";

				return {
					content: [
						{
							type: "text",
							text: `${greeting} This message is from an MCP tool! 🎉`,
						},
					],
				};
			} catch (err) {
				// Log error to dashboard with full error object
				console.error("say_hello tool error:", err);
				throw err;
			}
		},
	);
};