Add outputSchema support to fix MCP tool validation errors

src/http-server.ts

@@ -2,6 +2,7 @@
 
 import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
 import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
+import { Transport } from "@modelcontextprotocol/sdk/shared/transport.js";
 import { isInitializeRequest } from "@modelcontextprotocol/sdk/types.js";
 import express from "express";
 import { randomUUID } from "node:crypto";
@@ -62,9 +63,7 @@ export async function main() {
         // Create and connect server first
         const server = createServer();
         // The transport will have sessionId after initialization
-        await server.connect(
-          transport as StreamableHTTPServerTransport & { sessionId: string }
-        );
+        await server.connect(transport as Transport);
 
         // Log after successful connection
         logger.info("New MCP session server connected", {

src/mcp/tools/application/applicationCreate.ts

@@ -1,7 +1,6 @@
 import { z } from "zod";
 import apiClient from "../../../utils/apiClient.js";
 import { createTool } from "../toolFactory.js";
-import { ResponseFormatter } from "../../../utils/responseFormatter.js";
 
 export const applicationCreate = createTool({
   name: "application-create",
@@ -29,6 +28,14 @@ export const applicationCreate = createTool({
       .optional()
       .describe("The ID of the server where the application will be deployed."),
   }),
+  outputSchema: z.object({
+    success: z.boolean().describe("Whether the operation was successful"),
+    message: z.string().describe("A message describing the result"),
+    data: z
+      .record(z.any())
+      .optional()
+      .describe("The application data returned from the API"),
+  }),
   annotations: {
     title: "Create Application",
     destructiveHint: false,
@@ -38,9 +45,20 @@ export const applicationCreate = createTool({
   handler: async (input) => {
     const response = await apiClient.post("/application.create", input);
 
-    return ResponseFormatter.success(
-      `Application "${input.name}" created successfully in environment "${input.environmentId}"`,
-      response.data
-    );
+    const structuredData = {
+      success: true,
+      message: `Application "${input.name}" created successfully in environment "${input.environmentId}"`,
+      data: response.data,
+    };
+
+    return {
+      content: [
+        {
+          type: "text",
+          text: JSON.stringify(structuredData, null, 2),
+        },
+      ],
+      structuredContent: structuredData,
+    };
   },
 });

src/mcp/tools/toolFactory.ts

@@ -11,10 +11,15 @@ export type ToolHandler<T> = (input: T) => Promise<{
 
 // Defines the structure for a tool.
 // TShape is the ZodRawShape (the object passed to z.object()).
-export interface ToolDefinition<TShape extends ZodRawShape> {
+// TOutputShape is the optional output schema ZodRawShape
+export interface ToolDefinition<
+  TShape extends ZodRawShape,
+  TOutputShape extends ZodRawShape = ZodRawShape,
+> {
   name: string;
   description: string;
   schema: ZodObject<TShape>; // The schema must be a ZodObject
+  outputSchema?: ZodObject<TOutputShape>; // Optional output schema for validation
   handler: ToolHandler<z.infer<ZodObject<TShape>>>; // Handler input is inferred from the ZodObject
   annotations?: {
     title?: string;
@@ -39,9 +44,12 @@ export function createToolContext(): ToolContext {
   };
 }
 
-export function createTool<TShape extends import("zod").ZodRawShape>(
-  definition: ToolDefinition<TShape>
-): ToolDefinition<TShape> {
+export function createTool<
+  TShape extends import("zod").ZodRawShape,
+  TOutputShape extends import("zod").ZodRawShape = import("zod").ZodRawShape,
+>(
+  definition: ToolDefinition<TShape, TOutputShape>
+): ToolDefinition<TShape, TOutputShape> {
   return {
     ...definition,
     handler: async (input) => {

src/server.ts

@@ -8,7 +8,16 @@ export function createServer() {
   });
 
   for (const tool of allTools) {
-    server.tool(tool.name, tool.description, tool.schema.shape, tool.handler);
+    server.registerTool(
+      tool.name,
+      {
+        description: tool.description,
+        inputSchema: tool.schema.shape,
+        ...(tool.outputSchema && { outputSchema: tool.outputSchema.shape }),
+        ...(tool.annotations && { annotations: tool.annotations }),
+      },
+      tool.handler
+    );
   }
 
   return server;