fix: repeat MCP tool data as JSON text for clients without structured content

src/tools/mcp/mcp.test.mjs

@@ -125,7 +125,10 @@ test('tool results carry text and structured content; failures stay generic', as
     (await request('tools/call', { name: 'count', arguments: { n: 3 } }))
       .result,
     {
-      content: [{ type: 'text', text: '3 things.' }],
+      content: [
+        { type: 'text', text: '3 things.' },
+        { type: 'text', text: '{"n":3}' },
+      ],
       structuredContent: { n: 3 },
       isError: false,
     },

src/tools/mcp/protocol.js

@@ -80,8 +80,11 @@ export function createMcpServer({
           signal,
         });
         return {
+          // The data is repeated as JSON text for clients that do not read
+          // structuredContent.
           content: [
             { type: 'text', text: result.summary },
+            { type: 'text', text: JSON.stringify(result.data) },
             ...(result.images || []).map((item) => ({
               type: 'image',
               data: item.data,