feat: add outputSchema to all example servers

Define output schemas for structuredContent validation:
- basic-server-vanillajs: { time: string }
- budget-allocator-server: BudgetDataResponseSchema
- cohort-heatmap-server: CohortDataSchema
- customer-segmentation-server: customers/segments schema
- integration-server: { time: string }
- scenario-modeler-server: templates/defaultInputs schema
- system-monitor-server: SystemStatsSchema
- threejs-server: { code, height }
- video-resource-server: { videoUri, description }
- wiki-explorer-server: { page, links, error }

Author: ochafik

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";
 
@@ -28,6 +29,9 @@ 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> => {

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> => {

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

@@ -607,7 +607,7 @@ const app = new App({ name: "Budget Allocator", version: "1.0.0" });
 
 app.ontoolresult = (result) => {
   log.info("Received tool result:", result);
-  const data = result.structuredContent 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 }) => {

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

@@ -123,7 +123,7 @@ function CohortHeatmapInner({
           maxPeriods: 12,
         },
       });
-      setData(result.structuredContent 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;
@@ -78,6 +101,7 @@ 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> => {

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,
@@ -33,6 +34,9 @@ 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> => {

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: {

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

@@ -58,7 +58,7 @@ function ScenarioModeler() {
     onAppCreated: (app) => {
       app.ontoolresult = async (result) => {
         const { templates, defaultInputs } =
-          result.structuredContent as CallToolResultData;
+          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> => {