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

docs/TOOLS.md

@@ -32,7 +32,8 @@ checks completely; unsupported keywords are rejected at definition time.
 `run(args, { services, signal })` resolves to `{ summary, data }`: one sentence
 for people and a structured object for programs. A tool may also return `images`,
 each `{ mimeType, data }` with base64 data; the MCP adapter sends them as image
-content.
+content. MCP results carry the summary and the data as JSON text, plus the data
+as `structuredContent`, for clients that read only one of them.
 
 `composeCatalog({ tools, services, replace, interceptors })` builds a catalog:
 

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,

src/tools/queries/media.test.mjs

@@ -97,7 +97,7 @@ test('a snapshot returns the frame as an image with its credit', async () => {
     method: 'tools/call',
     params: { name: 'get_cctv_snapshot', arguments: { camera_id: 'austin-1' } },
   });
-  assert.deepEqual(response.result.content[1], {
+  assert.deepEqual(response.result.content[2], {
     type: 'image',
     data: 'iVBORw0KGgo=',
     mimeType: 'image/png',