update to track spec changes

Author: bhosmer-ant

src/examples/client/testOutputSchemaServers.ts

@@ -45,21 +45,26 @@ server.registerTool(
     const temp_c = Math.round((Math.random() * 35 - 5) * 10) / 10;
     const conditions = ["sunny", "cloudy", "rainy", "stormy", "snowy"][Math.floor(Math.random() * 5)];
 
-    return {
-      content: [],
-      structuredContent: {
-        temperature: {
-          celsius: temp_c,
-          fahrenheit: Math.round((temp_c * 9 / 5 + 32) * 10) / 10
-        },
-        conditions,
-        humidity: Math.round(Math.random() * 100),
-        wind: {
-          speed_kmh: Math.round(Math.random() * 50),
-          direction: ["N", "NE", "E", "SE", "S", "SW", "W", "NW"][Math.floor(Math.random() * 8)]
-        }
+    const structuredContent = {
+      temperature: {
+        celsius: temp_c,
+        fahrenheit: Math.round((temp_c * 9 / 5 + 32) * 10) / 10
+      },
+      conditions,
+      humidity: Math.round(Math.random() * 100),
+      wind: {
+        speed_kmh: Math.round(Math.random() * 50),
+        direction: ["N", "NE", "E", "SE", "S", "SW", "W", "NW"][Math.floor(Math.random() * 8)]
       }
     };
+
+    return {
+      content: [{
+        type: "text",
+        text: JSON.stringify(structuredContent, null, 2)
+      }],
+      structuredContent
+    };
   }
 );
 

src/examples/server/lowLevelOutputSchema.ts

@@ -1224,18 +1224,15 @@ describe("tool()", () => {
       mcpServer.server.connect(serverTransport),
     ]);
 
-    // First call listTools to cache the outputSchema in the client
-    await client.listTools();
-
-    // Call the tool and expect it to throw a validation error
+    // Call the tool and expect it to throw a server-side validation error
     await expect(
       client.callTool({
         name: "test",
         arguments: {
           input: "hello",
         },
       }),
-    ).rejects.toThrow(/Structured content does not match the tool's output schema/);
+    ).rejects.toThrow(/Invalid structured content for tool test/);
   });
 
   /***

src/examples/server/mcpServerOutputSchema.ts

@@ -198,40 +198,15 @@ export class McpServer {
           }
         }
 
-        // Handle structured output and backward compatibility
-        if (tool.outputSchema) {
-          // Tool has outputSchema, so result must have structuredContent (unless it's an error)
-          if (!result.structuredContent && !result.isError) {
-            throw new McpError(
-              ErrorCode.InternalError,
-              `Tool ${request.params.name} has outputSchema but returned no structuredContent`,
-            );
-          }
-
-          // For backward compatibility, if structuredContent is provided but no content,
-          // automatically serialize the structured content to text
-          if (result.structuredContent && !result.content) {
-            result.content = [
-              {
-                type: "text",
-                text: JSON.stringify(result.structuredContent, null, 2),
-              },
-            ];
-          }
-        } else {
-          // Tool must have content if no outputSchema
-          if (!result.content && !result.isError) {
-            throw new McpError(
-              ErrorCode.InternalError,
-              `Tool ${request.params.name} has no outputSchema and must return content`,
-            );
-          }
-
-          // If structuredContent is provided, it's an error
-          if (result.structuredContent) {
+        if (tool.outputSchema && result.structuredContent) {
+          // if the tool has an output schema, validate structured content
+          const parseResult = await tool.outputSchema.safeParseAsync(
+            result.structuredContent,
+          );
+          if (!parseResult.success) {
             throw new McpError(
-              ErrorCode.InternalError,
-              `Tool ${request.params.name} has no outputSchema but returned structuredContent`,
+              ErrorCode.InvalidParams,
+              `Invalid structured content for tool ${request.params.name}: ${parseResult.error.message}`,
             );
           }
         }