diff --git a/src/filesystem/__tests__/structured-content.test.ts b/src/filesystem/__tests__/structured-content.test.ts
index 4b8f92b0a3..5f9d01c943 100644
--- a/src/filesystem/__tests__/structured-content.test.ts
+++ b/src/filesystem/__tests__/structured-content.test.ts
@@ -62,6 +62,7 @@ describe('structuredContent schema compliance', () => {
 
       // structuredContent.content should be a string (matching outputSchema: { content: z.string() })
       const structuredContent = result.structuredContent as { content: unknown };
+      expect(Object.keys(structuredContent)).toEqual(['content']);
       expect(typeof structuredContent.content).toBe('string');
 
       // It should NOT be an array
@@ -85,6 +86,7 @@ describe('structuredContent schema compliance', () => {
 
       // structuredContent.content should be a string (matching outputSchema: { content: z.string() })
       const structuredContent = result.structuredContent as { content: unknown };
+      expect(Object.keys(structuredContent)).toEqual(['content']);
       expect(typeof structuredContent.content).toBe('string');
 
       // It should NOT be an array
@@ -113,6 +115,7 @@ describe('structuredContent schema compliance', () => {
 
       // structuredContent.content should be a string (matching outputSchema: { content: z.string() })
       const structuredContent = result.structuredContent as { content: unknown };
+      expect(Object.keys(structuredContent)).toEqual(['content']);
       expect(typeof structuredContent.content).toBe('string');
 
       // It should NOT be an array
@@ -133,6 +136,7 @@ describe('structuredContent schema compliance', () => {
       expect(result.structuredContent).toBeDefined();
 
       const structuredContent = result.structuredContent as { content: unknown };
+      expect(Object.keys(structuredContent)).toEqual(['content']);
       expect(typeof structuredContent.content).toBe('string');
       expect(Array.isArray(structuredContent.content)).toBe(false);
     });
@@ -151,6 +155,7 @@ describe('structuredContent schema compliance', () => {
       expect(result.structuredContent).toBeDefined();
 
       const structuredContent = result.structuredContent as { content: unknown };
+      expect(Object.keys(structuredContent)).toEqual(['content']);
       expect(typeof structuredContent.content).toBe('string');
       expect(Array.isArray(structuredContent.content)).toBe(false);
     });
diff --git a/src/filesystem/index.ts b/src/filesystem/index.ts
index 7b67e63e58..7faf5e0661 100644
--- a/src/filesystem/index.ts
+++ b/src/filesystem/index.ts
@@ -185,6 +185,13 @@ async function readFileAsBase64Stream(filePath: string): Promise<string> {
   });
 }
 
+function asTextToolResult(text: string): CallToolResult {
+  return {
+    content: [{ type: "text", text }],
+    structuredContent: { content: text },
+  };
+}
+
 // Tool registrations
 
 // read_file (deprecated) and read_text_file
@@ -204,10 +211,7 @@ const readTextFileHandler = async (args: z.infer<typeof ReadTextFileArgsSchema>)
     content = await readFileContent(validPath);
   }
 
-  return {
-    content: [{ type: "text" as const, text: content }],
-    structuredContent: { content }
-  };
+  return asTextToolResult(content);
 };
 
 server.registerTool(
@@ -329,10 +333,7 @@ server.registerTool(
       }),
     );
     const text = results.join("\n---\n");
-    return {
-      content: [{ type: "text" as const, text }],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );
 
@@ -355,10 +356,7 @@ server.registerTool(
     const validPath = await validatePath(args.path);
     await writeFileContent(validPath, args.content);
     const text = `Successfully wrote to ${args.path}`;
-    return {
-      content: [{ type: "text" as const, text }],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );
 
@@ -384,10 +382,7 @@ server.registerTool(
   async (args: z.infer<typeof EditFileArgsSchema>) => {
     const validPath = await validatePath(args.path);
     const result = await applyFileEdits(validPath, args.edits, args.dryRun);
-    return {
-      content: [{ type: "text" as const, text: result }],
-      structuredContent: { content: result }
-    };
+    return asTextToolResult(result);
   }
 );
 
@@ -410,10 +405,7 @@ server.registerTool(
     const validPath = await validatePath(args.path);
     await fs.mkdir(validPath, { recursive: true });
     const text = `Successfully created directory ${args.path}`;
-    return {
-      content: [{ type: "text" as const, text }],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );
 
@@ -438,10 +430,7 @@ server.registerTool(
     const formatted = entries
       .map((entry) => `${entry.isDirectory() ? "[DIR]" : "[FILE]"} ${entry.name}`)
       .join("\n");
-    return {
-      content: [{ type: "text" as const, text: formatted }],
-      structuredContent: { content: formatted }
-    };
+    return asTextToolResult(formatted);
   }
 );
 
@@ -516,11 +505,7 @@ server.registerTool(
     ];
 
     const text = [...formattedEntries, ...summary].join("\n");
-    const contentBlock = { type: "text" as const, text };
-    return {
-      content: [contentBlock],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );
 
@@ -586,11 +571,7 @@ server.registerTool(
 
     const treeData = await buildTree(rootPath, args.excludePatterns);
     const text = JSON.stringify(treeData, null, 2);
-    const contentBlock = { type: "text" as const, text };
-    return {
-      content: [contentBlock],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );
 
@@ -615,11 +596,7 @@ server.registerTool(
     const validDestPath = await validatePath(args.destination);
     await fs.rename(validSourcePath, validDestPath);
     const text = `Successfully moved ${args.source} to ${args.destination}`;
-    const contentBlock = { type: "text" as const, text };
-    return {
-      content: [contentBlock],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );
 
@@ -645,10 +622,7 @@ server.registerTool(
     const validPath = await validatePath(args.path);
     const results = await searchFilesWithValidation(validPath, args.pattern, allowedDirectories, { excludePatterns: args.excludePatterns });
     const text = results.length > 0 ? results.join("\n") : "No matches found";
-    return {
-      content: [{ type: "text" as const, text }],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );
 
@@ -673,10 +647,7 @@ server.registerTool(
     const text = Object.entries(info)
       .map(([key, value]) => `${key}: ${value}`)
       .join("\n");
-    return {
-      content: [{ type: "text" as const, text }],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );
 
@@ -695,10 +666,7 @@ server.registerTool(
   },
   async () => {
     const text = `Allowed directories:\n${allowedDirectories.join('\n')}`;
-    return {
-      content: [{ type: "text" as const, text }],
-      structuredContent: { content: text }
-    };
+    return asTextToolResult(text);
   }
 );