HackerNews MCP Server

Instructions

Implementation Reference

• src/tools/get-item.ts:50-74 (handler)

  The primary handler function that executes the 'get-item' tool logic: validates input, fetches the HackerNews item by ID using HNAPIClient (including full nested comment tree), checks existence, validates output, and returns success or error result.
  export async function getItemHandler(input: unknown): Promise<CallToolResult> { try { // Validate input const validatedParams = GetItemInputSchema.parse(input); // Create API client const client = new HNAPIClient(); // Call items API to get item with nested children const result = await client.getItem(validatedParams.itemId); // Check if item exists const notFoundError = checkItemExists(result, "Item", validatedParams.itemId); if (notFoundError) { return notFoundError; } // Validate output const validatedResult = GetItemOutputSchema.parse(result); return createSuccessResult(validatedResult); } catch (error) { return handleAPIError(error, "get-item"); } }
• src/tools/get-item.ts:16-37 (schema)

  Zod schemas defining input (GetItemInputSchema: itemId string) and output (GetItemOutputSchema: full item fields including nested children) for validation in the get-item tool.
  export const GetItemInputSchema = z.object({ itemId: z.string().min(1, "itemId must not be empty").describe("HackerNews item ID"), }); /** * Output schema for get-item tool (ItemResult with nested children) */ export const GetItemOutputSchema = z.object({ id: z.string(), created_at: z.string().datetime(), created_at_i: z.number().int().positive(), type: z.enum(["story", "comment", "poll", "pollopt"]), author: z.string(), title: z.string().nullable(), url: z.string().url().nullable(), text: z.string().nullable(), points: z.number().int().nonnegative().nullable(), parent_id: z.number().int().positive().nullable(), story_id: z.number().int().positive(), options: z.array(z.number().int()), children: z.array(z.any()), // Recursive type, validated at runtime });
• src/tools/get-item.ts:79-112 (registration)

  Tool metadata (getItemTool) for MCP registration: name, detailed description, and JSON schema for input validation.
  export const getItemTool = { name: "get-item", description: `Retrieve detailed information about a specific HackerNews item by ID. Returns complete item details including the full nested comment tree. Use this to: - View a story with all comments - Read a specific comment with its replies - Explore discussion threads in depth - Get complete metadata for any item Features: - Full nested comment tree (all levels) - Complete item metadata (title, url, text, points, author, etc.) - Works for stories, comments, polls, and poll options - Includes creation time and item type Examples: - Get story with comments: { "itemId": "38456789" } - Get specific comment: { "itemId": "38456790" } - Get poll: { "itemId": "126809" } Note: Large comment threads (>500 comments) may take 2-3 seconds to load due to nested fetching. Returns error if item doesn't exist or has been deleted.`, inputSchema: { type: "object", properties: { itemId: { type: "string", description: "HackerNews item ID (e.g., '38456789')", }, }, required: ["itemId"], }, };
• src/index.ts:45-55 (registration)

  Registration of getItemTool in the server's ListToolsRequestHandler response, making it discoverable by MCP clients.
  server.setRequestHandler(ListToolsRequestSchema, async () => { return { tools: [ searchPostsToolMetadata, getFrontPageTool, getLatestPostsTool, getItemTool, getUserTool, ], }; });
• src/index.ts:75-76 (registration)

  Dispatch registration in the central CallToolRequestHandler switch statement, routing 'get-item' calls to getItemHandler.
  case "get-item": return await getItemHandler(args);