Refactor/expand into a more substantial example

Author: jspahrsummers

template/src/index.ts.ejs

@@ -1,12 +1,38 @@
-#!/usr/bin/env node
+/**
+ * This is a template MCP server that implements a simple notes system.
+ * It demonstrates core MCP concepts like resources and tools by allowing:
+ * - Listing notes as resources
+ * - Reading individual notes
+ * - Creating new notes via a tool
+ */
 
 import { Server } from "@modelcontextprotocol/sdk/server/index.js";
 import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
 import {
+  CallToolRequestSchema,
   ListResourcesRequestSchema,
   ListToolsRequestSchema,
+  ReadResourceRequestSchema,
 } from "@modelcontextprotocol/sdk/types.js";
 
+/**
+ * Type alias for a note object.
+ */
+type Note = { title: string, content: string };
+
+/**
+ * Simple in-memory storage for notes.
+ * In a real implementation, this would likely be backed by a database.
+ */
+const notes: { [id: string]: Note } = {
+  "1": { title: "First Note", content: "This is note 1" },
+  "2": { title: "Second Note", content: "This is note 2" }
+};
+
+/**
+ * Create an MCP server with capabilities for resources (to list/read notes)
+ * and tools (to create new notes).
+ */
 const server = new Server(
   {
     name: "<%= name %>",
@@ -17,41 +43,111 @@ const server = new Server(
       resources: {},
       tools: {},
     },
-  },
+  }
 );
 
+/**
+ * Handler for listing available notes as resources.
+ * Each note is exposed as a resource with:
+ * - A note:// URI scheme
+ * - Plain text MIME type
+ * - Human readable name and description (now including the note title)
+ */
 server.setRequestHandler(ListResourcesRequestSchema, async () => {
   return {
-    resources: [
-      {
-        uri: "example://hello",
-        mimeType: "text/plain",
-        name: "Example resource",
-      },
-    ],
+    resources: Object.entries(notes).map(([id, note]) => ({
+      uri: `note:///${id}`,
+      mimeType: "text/plain",
+      name: note.title,
+      description: `A text note: ${note.title}`
+    }))
+  };
+});
+
+/**
+ * Handler for reading the contents of a specific note.
+ * Takes a note:// URI and returns the note content as plain text.
+ */
+server.setRequestHandler(ReadResourceRequestSchema, async (request) => {
+  const url = new URL(request.params.uri);
+  const id = url.pathname.replace(/^\//, '');
+  const note = notes[id];
+
+  if (!note) {
+    throw new Error(`Note ${id} not found`);
+  }
+
+  return {
+    contents: [{
+      uri: request.params.uri,
+      mimeType: "text/plain",
+      text: note.content
+    }]
   };
 });
 
+/**
+ * Handler that lists available tools.
+ * Exposes a single "create_note" tool that lets clients create new notes.
+ */
 server.setRequestHandler(ListToolsRequestSchema, async () => {
   return {
     tools: [
       {
-        name: "example",
-        description: "An example tool",
+        name: "create_note",
+        description: "Create a new note",
         inputSchema: {
           type: "object",
           properties: {
-            message: {
+            title: {
               type: "string",
-              description: "Message to echo",
+              description: "Title of the note"
             },
+            content: {
+              type: "string",
+              description: "Text content of the note"
+            }
           },
-        },
-      },
-    ],
+          required: ["title", "content"]
+        }
+      }
+    ]
   };
 });
 
+/**
+ * Handler for the create_note tool.
+ * Creates a new note with the provided title and content, and returns success message.
+ */
+server.setRequestHandler(CallToolRequestSchema, async (request) => {
+  switch (request.params.name) {
+    case "create_note": {
+      const title = String(request.params.arguments?.title);
+      const content = String(request.params.arguments?.content);
+      if (!title || !content) {
+        throw new Error("Title and content are required");
+      }
+
+      const id = String(Object.keys(notes).length + 1);
+      notes[id] = { title, content };
+
+      return {
+        content: [{
+          type: "text",
+          text: `Created note ${id}: ${title}`
+        }]
+      };
+    }
+
+    default:
+      throw new Error("Unknown tool");
+  }
+});
+
+/**
+ * Start the server using stdio transport.
+ * This allows the server to communicate via standard input/output streams.
+ */
 async function main() {
   const transport = new StdioServerTransport();
   await server.connect(transport);