feat: use structuredContent with outputSchema in example servers

examples/basic-server-vanillajs/server.ts

@@ -3,6 +3,7 @@ import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"
 import type { CallToolResult, ReadResourceResult } from "@modelcontextprotocol/sdk/types.js";
 import fs from "node:fs/promises";
 import path from "node:path";
+import { z } from "zod";
 import { registerAppTool, registerAppResource, RESOURCE_MIME_TYPE, RESOURCE_URI_META_KEY } from "@modelcontextprotocol/ext-apps/server";
 import { startServer } from "./server-utils.js";
 
@@ -28,12 +29,17 @@ export function createServer(): McpServer {
       title: "Get Time",
       description: "Returns the current server time as an ISO 8601 string.",
       inputSchema: {},
+      outputSchema: z.object({
+        time: z.string(),
+      }),
       _meta: { [RESOURCE_URI_META_KEY]: RESOURCE_URI },
     },
     async (): Promise<CallToolResult> => {
       const time = new Date().toISOString();
+      const data = { time };
       return {
-        content: [{ type: "text", text: JSON.stringify({ time }) }],
+        content: [{ type: "text", text: JSON.stringify(data) }],
+        structuredContent: data,
       };
     },
   );

examples/basic-server-vanillajs/src/mcp-app.ts

@@ -15,8 +15,8 @@ const log = {
 
 
 function extractTime(result: CallToolResult): string {
-  const { text } = result.content?.find((c) => c.type === "text")!;
-  return text;
+  const data = result.structuredContent as { time: string };
+  return data.time;
 }
 
 

examples/budget-allocator-server/server.ts

@@ -248,6 +248,7 @@ export function createServer(): McpServer {
       description:
         "Returns budget configuration with 24 months of historical allocations and industry benchmarks by company stage",
       inputSchema: {},
+      outputSchema: BudgetDataResponseSchema,
       _meta: { [RESOURCE_URI_META_KEY]: resourceUri },
     },
     async (): Promise<CallToolResult> => {
@@ -279,6 +280,7 @@ export function createServer(): McpServer {
             text: JSON.stringify(response),
           },
         ],
+        structuredContent: response,
       };
     },
   );

examples/budget-allocator-server/src/mcp-app.ts

@@ -607,13 +607,7 @@ const app = new App({ name: "Budget Allocator", version: "1.0.0" });
 
 app.ontoolresult = (result) => {
   log.info("Received tool result:", result);
-  const text = result
-    .content!.filter(
-      (c): c is { type: "text"; text: string } => c.type === "text",
-    )
-    .map((c) => c.text)
-    .join("");
-  const data = JSON.parse(text) as BudgetDataResponse;
+  const data = result.structuredContent as unknown as BudgetDataResponse;
   if (data?.config && data?.analytics) {
     initializeUI(data.config, data.analytics);
   }

examples/cohort-heatmap-server/server.ts

@@ -169,6 +169,7 @@ export function createServer(): McpServer {
       description:
         "Returns cohort retention heatmap data showing customer retention over time by signup month",
       inputSchema: GetCohortDataInputSchema.shape,
+      outputSchema: CohortDataSchema.shape,
       _meta: { [RESOURCE_URI_META_KEY]: resourceUri },
     },
     async ({ metric, periodType, cohortCount, maxPeriods }) => {
@@ -181,6 +182,7 @@ export function createServer(): McpServer {
 
       return {
         content: [{ type: "text", text: JSON.stringify(data) }],
+        structuredContent: data,
       };
     },
   );

examples/cohort-heatmap-server/src/mcp-app.tsx

@@ -123,13 +123,7 @@ function CohortHeatmapInner({
           maxPeriods: 12,
         },
       });
-      const text = result
-        .content!.filter(
-          (c): c is { type: "text"; text: string } => c.type === "text",
-        )
-        .map((c) => c.text)
-        .join("");
-      setData(JSON.parse(text) as CohortData);
+      setData(result.structuredContent as unknown as CohortData);
     } catch (e) {
       console.error("Failed to fetch cohort data:", e);
     } finally {

examples/customer-segmentation-server/server.ts

@@ -30,6 +30,29 @@ const GetCustomerDataInputSchema = z.object({
     .describe("Filter by segment (default: All)"),
 });
 
+const CustomerSchema = z.object({
+  id: z.string(),
+  name: z.string(),
+  segment: z.string(),
+  annualRevenue: z.number(),
+  employeeCount: z.number(),
+  accountAge: z.number(),
+  engagementScore: z.number(),
+  supportTickets: z.number(),
+  nps: z.number(),
+});
+
+const SegmentSummarySchema = z.object({
+  name: z.string(),
+  count: z.number(),
+  color: z.string(),
+});
+
+const GetCustomerDataOutputSchema = z.object({
+  customers: z.array(CustomerSchema),
+  segments: z.array(SegmentSummarySchema),
+});
+
 // Cache generated data for session consistency
 let cachedCustomers: Customer[] | null = null;
 let cachedSegments: SegmentSummary[] | null = null;
@@ -78,13 +101,15 @@ export function createServer(): McpServer {
         description:
           "Returns customer data with segment information for visualization. Optionally filter by segment.",
         inputSchema: GetCustomerDataInputSchema.shape,
+        outputSchema: GetCustomerDataOutputSchema.shape,
         _meta: { [RESOURCE_URI_META_KEY]: resourceUri },
       },
       async ({ segment }): Promise<CallToolResult> => {
         const data = getCustomerData(segment);
 
         return {
           content: [{ type: "text", text: JSON.stringify(data) }],
+          structuredContent: data,
         };
       },
     );

examples/integration-server/server.ts

@@ -6,6 +6,7 @@ import type {
 } from "@modelcontextprotocol/sdk/types.js";
 import fs from "node:fs/promises";
 import path from "node:path";
+import { z } from "zod";
 import {
   registerAppTool,
   registerAppResource,
@@ -33,16 +34,21 @@ export function createServer(): McpServer {
       title: "Get Time",
       description: "Returns the current server time.",
       inputSchema: {},
+      outputSchema: z.object({
+        time: z.string(),
+      }),
       _meta: { [RESOURCE_URI_META_KEY]: RESOURCE_URI },
     },
     async (): Promise<CallToolResult> => {
+      const time = new Date().toISOString();
       return {
         content: [
           {
             type: "text",
-            text: JSON.stringify({ time: new Date().toISOString() }),
+            text: JSON.stringify({ time }),
           },
         ],
+        structuredContent: { time },
       };
     },
   );

examples/integration-server/src/mcp-app.tsx

@@ -17,13 +17,7 @@ const log = {
 };
 
 function extractTime(callToolResult: CallToolResult): string {
-  const text = callToolResult
-    .content!.filter(
-      (c): c is { type: "text"; text: string } => c.type === "text",
-    )
-    .map((c) => c.text)
-    .join("");
-  const { time } = JSON.parse(text) as { time: string };
+  const { time } = callToolResult.structuredContent as { time: string };
   return time;
 }
 

examples/scenario-modeler-server/server.ts

@@ -64,6 +64,13 @@ const GetScenarioDataInputSchema = z.object({
   ),
 });
 
+const GetScenarioDataOutputSchema = z.object({
+  templates: z.array(ScenarioTemplateSchema),
+  defaultInputs: ScenarioInputsSchema,
+  customProjections: z.array(MonthlyProjectionSchema).optional(),
+  customSummary: ScenarioSummarySchema.optional(),
+});
+
 // Types derived from schemas
 type ScenarioInputs = z.infer<typeof ScenarioInputsSchema>;
 type MonthlyProjection = z.infer<typeof MonthlyProjectionSchema>;
@@ -269,6 +276,7 @@ export function createServer(): McpServer {
         description:
           "Returns SaaS scenario templates and optionally computes custom projections for given inputs",
         inputSchema: GetScenarioDataInputSchema.shape,
+        outputSchema: GetScenarioDataOutputSchema.shape,
         _meta: { [RESOURCE_URI_META_KEY]: resourceUri },
       },
       async (args: {
@@ -278,18 +286,21 @@ export function createServer(): McpServer {
           ? calculateScenario(args.customInputs)
           : undefined;
 
+        const data = {
+          templates: SCENARIO_TEMPLATES,
+          defaultInputs: DEFAULT_INPUTS,
+          customProjections: customScenario?.projections,
+          customSummary: customScenario?.summary,
+        };
+
         return {
           content: [
             {
               type: "text",
-              text: JSON.stringify({
-                templates: SCENARIO_TEMPLATES,
-                defaultInputs: DEFAULT_INPUTS,
-                customProjections: customScenario?.projections,
-                customSummary: customScenario?.summary,
-              }),
+              text: JSON.stringify(data),
             },
           ],
+          structuredContent: data,
         };
       },
     );

examples/scenario-modeler-server/src/mcp-app.tsx

@@ -1,6 +1,5 @@
 import type { McpUiHostContext } from "@modelcontextprotocol/ext-apps";
 import { useApp } from "@modelcontextprotocol/ext-apps/react";
-import type { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
 import { StrictMode, useState, useMemo, useCallback, useEffect } from "react";
 import { createRoot } from "react-dom/client";
 import { SliderRow } from "./components/SliderRow.tsx";
@@ -25,18 +24,6 @@ interface CallToolResultData {
   defaultInputs?: ScenarioInputs;
 }
 
-/** Extract templates and defaultInputs from tool result content */
-function extractResultData(result: CallToolResult): CallToolResultData {
-  const text = result
-    .content!.filter(
-      (c): c is { type: "text"; text: string } => c.type === "text",
-    )
-    .map((c) => c.text)
-    .join("");
-  const { templates, defaultInputs } = JSON.parse(text) as CallToolResultData;
-  return { templates, defaultInputs };
-}
-
 const APP_INFO = { name: "SaaS Scenario Modeler", version: "1.0.0" };
 
 function getSafeAreaPaddingStyle(hostContext?: McpUiHostContext) {
@@ -70,7 +57,8 @@ function ScenarioModeler() {
     capabilities: {},
     onAppCreated: (app) => {
       app.ontoolresult = async (result) => {
-        const { templates, defaultInputs } = extractResultData(result);
+        const { templates, defaultInputs } =
+          result.structuredContent as unknown as CallToolResultData;
         if (templates) setTemplates(templates);
         if (defaultInputs) setDefaultInputs(defaultInputs);
       };

examples/system-monitor-server/server.ts

@@ -124,6 +124,7 @@ export function createServer(): McpServer {
       description:
         "Returns current system statistics including per-core CPU usage, memory, and system info.",
       inputSchema: {},
+      outputSchema: SystemStatsSchema.shape,
       _meta: { [RESOURCE_URI_META_KEY]: resourceUri },
     },
     async (): Promise<CallToolResult> => {
@@ -151,6 +152,7 @@ export function createServer(): McpServer {
 
       return {
         content: [{ type: "text", text: JSON.stringify(stats) }],
+        structuredContent: stats,
       };
     },
   );

examples/system-monitor-server/src/mcp-app.ts

@@ -265,13 +265,7 @@ async function fetchStats(): Promise<void> {
       arguments: {},
     });
 
-    const text = result
-      .content!.filter(
-        (c): c is { type: "text"; text: string } => c.type === "text",
-      )
-      .map((c) => c.text)
-      .join("");
-    const stats = JSON.parse(text) as SystemStats;
+    const stats = result.structuredContent as unknown as SystemStats;
 
     // Initialize chart on first data if needed
     if (!state.chart && stats.cpu.count > 0) {

examples/threejs-server/server.ts

@@ -166,16 +166,17 @@ export function createServer(): McpServer {
           .default(400)
           .describe("Height in pixels"),
       },
+      outputSchema: z.object({
+        code: z.string(),
+        height: z.number(),
+      }),
       _meta: { [RESOURCE_URI_META_KEY]: resourceUri },
     },
     async ({ code, height }) => {
+      const data = { code, height };
       return {
-        content: [
-          {
-            type: "text",
-            text: JSON.stringify({ code, height }),
-          },
-        ],
+        content: [{ type: "text", text: JSON.stringify(data) }],
+        structuredContent: data,
       };
     },
   );

examples/video-resource-server/server.ts

@@ -129,20 +129,21 @@ ${Object.entries(VIDEO_LIBRARY)
             `Video ID to play. Available: ${Object.keys(VIDEO_LIBRARY).join(", ")}`,
           ),
       },
+      outputSchema: z.object({
+        videoUri: z.string(),
+        description: z.string(),
+      }),
       _meta: { [RESOURCE_URI_META_KEY]: RESOURCE_URI },
     },
     async ({ videoId }): Promise<CallToolResult> => {
       const video = VIDEO_LIBRARY[videoId];
+      const data = {
+        videoUri: `videos://${videoId}`,
+        description: video.description,
+      };
       return {
-        content: [
-          {
-            type: "text",
-            text: JSON.stringify({
-              videoUri: `videos://${videoId}`,
-              description: video.description,
-            }),
-          },
-        ],
+        content: [{ type: "text", text: JSON.stringify(data) }],
+        structuredContent: data,
       };
     },
   );

examples/video-resource-server/src/mcp-app.ts

@@ -28,18 +28,10 @@ const videoInfoEl = document.getElementById("video-info")!;
 function parseToolResult(
   result: CallToolResult,
 ): { videoUri: string; description: string } | null {
-  const text = result.content
-    ?.filter((c): c is { type: "text"; text: string } => c.type === "text")
-    .map((c) => c.text)
-    .join("");
-
-  if (!text) return null;
-
-  try {
-    return JSON.parse(text) as { videoUri: string; description: string };
-  } catch {
-    return null;
-  }
+  return result.structuredContent as {
+    videoUri: string;
+    description: string;
+  } | null;
 }
 
 // Show states