feat: mcp tools

examples/mcp.mjs

@@ -0,0 +1,101 @@
+import { z } from "zod";
+import { H3, serve, defineMcpHandler, defineMcpTool, defineMcpResource, defineMcpPrompt } from "h3";
+
+export const app = new H3();
+
+// --- Define MCP tools ---
+
+const echoTool = defineMcpTool({
+  name: "echo",
+  description: "Echo back a message",
+  inputSchema: { message: z.string().describe("The message to echo") },
+  handler: async ({ message }) => ({
+    content: [{ type: "text", text: message }],
+  }),
+});
+
+const calculatorTool = defineMcpTool({
+  name: "calculator",
+  description: "Perform basic math operations",
+  inputSchema: {
+    operation: z.enum(["add", "subtract", "multiply", "divide"]),
+    a: z.number().describe("First number"),
+    b: z.number().describe("Second number"),
+  },
+  handler: async ({ operation, a, b }) => {
+    let result;
+    switch (operation) {
+      case "add":
+        result = a + b;
+        break;
+      case "subtract":
+        result = a - b;
+        break;
+      case "multiply":
+        result = a * b;
+        break;
+      case "divide":
+        result = b !== 0 ? a / b : "Error: Division by zero";
+        break;
+    }
+    return {
+      content: [{ type: "text", text: JSON.stringify({ operation, a, b, result }, null, 2) }],
+    };
+  },
+});
+
+// --- Define MCP resources ---
+
+const aboutResource = defineMcpResource({
+  name: "about",
+  uri: "file:///about",
+  description: "Information about this MCP server",
+  handler: async (uri) => ({
+    contents: [
+      {
+        uri: uri.toString(),
+        text: "This is an example MCP server built with h3.",
+      },
+    ],
+  }),
+});
+
+// --- Define MCP prompts ---
+
+const summarizePrompt = defineMcpPrompt({
+  name: "summarize",
+  description: "Generate a prompt to summarize text",
+  argsSchema: {
+    text: z.string().describe("The text to summarize"),
+  },
+  handler: async ({ text }) => ({
+    messages: [
+      {
+        role: "user",
+        content: {
+          type: "text",
+          text: `Please summarize the following text:\n\n${text}`,
+        },
+      },
+    ],
+  }),
+});
+
+// --- Create the MCP handler ---
+
+app.all(
+  "/mcp",
+  defineMcpHandler({
+    name: "h3-mcp-example",
+    version: "1.0.0",
+    tools: [echoTool, calculatorTool],
+    resources: [aboutResource],
+    prompts: [summarizePrompt],
+  }),
+);
+
+// --- Landing page ---
+
+app.get("/", () => "MCP server running at /mcp");
+
+serve(app);

package.json

@@ -56,6 +56,7 @@
   "devDependencies": {
     "@happy-dom/global-registrator": "^20.5.0",
     "@mitata/counters": "^0.0.8",
+    "@modelcontextprotocol/sdk": "^1.26.0",
     "@types/connect": "^3.4.38",
     "@types/express": "^5.0.6",
     "@types/node": "^25.2.1",
@@ -92,11 +93,15 @@
     "zod": "^4.3.6"
   },
   "peerDependencies": {
+    "@modelcontextprotocol/sdk": "^1.25.0",
     "crossws": "^0.4.1"
   },
   "peerDependenciesMeta": {
     "crossws": {
       "optional": true
+    },
+    "@modelcontextprotocol/sdk": {
+      "optional": true
     }
   },
   "resolutions": {