feat(telemetry) Instrument traces with more attributes and make them available to OTEL users (#20237)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Jerop Kipruto <jerop@google.com>
Co-authored-by: MD. MOHIBUR RAHMAN <35300157+mrpmohiburrahman@users.noreply.github.com>
Co-authored-by: Jeffrey Ying <jeffrey.ying86@live.com>
Co-authored-by: Bryan Morgan <bryanmorgan@google.com>
Co-authored-by: joshualitt <joshualitt@google.com>
Co-authored-by: Dev Randalpura <devrandalpura@google.com>
Co-authored-by: Google Admin <github-admin@google.com>
Co-authored-by: Ben Knutson <benknutson@google.com>

packages/core/src/agents/subagent-tool.test.ts

@@ -23,10 +23,30 @@ import type {
   ToolInvocation,
   ToolResult,
 } from '../tools/tools.js';
+import {
+  GeminiCliOperation,
+  GEN_AI_AGENT_DESCRIPTION,
+  GEN_AI_AGENT_NAME,
+} from '../telemetry/constants.js';
 import type { ToolRegistry } from 'src/tools/tool-registry.js';
 
 vi.mock('./subagent-tool-wrapper.js');
 
+// Mock runInDevTraceSpan
+const runInDevTraceSpan = vi.hoisted(() =>
+  vi.fn(async (opts, fn) => {
+    const metadata = { attributes: opts.attributes || {} };
+    return fn({
+      metadata,
+      endSpan: vi.fn(),
+    });
+  }),
+);
+
+vi.mock('../telemetry/trace.js', () => ({
+  runInDevTraceSpan,
+}));
+
 const MockSubagentToolWrapper = vi.mocked(SubagentToolWrapper);
 
 const testDefinition: LocalAgentDefinition = {
@@ -155,6 +175,25 @@ describe('SubAgentInvocation', () => {
       abortSignal,
       updateOutput,
     );
+
+    expect(runInDevTraceSpan).toHaveBeenCalledWith(
+      expect.objectContaining({
+        operation: GeminiCliOperation.AgentCall,
+        attributes: expect.objectContaining({
+          [GEN_AI_AGENT_NAME]: testDefinition.name,
+          [GEN_AI_AGENT_DESCRIPTION]: testDefinition.description,
+        }),
+      }),
+      expect.any(Function),
+    );
+
+    // Verify metadata was set on the span
+    const spanCallback = vi.mocked(runInDevTraceSpan).mock.calls[0][1];
+    const mockMetadata = { input: undefined, output: undefined };
+    const mockSpan = { metadata: mockMetadata, endSpan: vi.fn() };
+    await spanCallback(mockSpan as Parameters<typeof spanCallback>[0]);
+    expect(mockMetadata.input).toBe(params);
+    expect(mockMetadata.output).toBe(mockResult);
   });
 
   describe('withUserHints', () => {

packages/core/src/agents/subagent-tool.ts

@@ -20,6 +20,12 @@ import type { AgentDefinition, AgentInputs } from './types.js';
 import { SubagentToolWrapper } from './subagent-tool-wrapper.js';
 import { SchemaValidator } from '../utils/schemaValidator.js';
 import { formatUserHintsForModel } from '../utils/fastAckHelper.js';
+import { runInDevTraceSpan } from '../telemetry/trace.js';
+import {
+  GeminiCliOperation,
+  GEN_AI_AGENT_DESCRIPTION,
+  GEN_AI_AGENT_NAME,
+} from '../telemetry/constants.js';
 
 export class SubagentTool extends BaseDeclarativeTool<AgentInputs, ToolResult> {
   constructor(
@@ -167,7 +173,21 @@ class SubAgentInvocation extends BaseToolInvocation<AgentInputs, ToolResult> {
       this.withUserHints(this.params),
     );
 
-    return invocation.execute(signal, updateOutput);
+    return runInDevTraceSpan(
+      {
+        operation: GeminiCliOperation.AgentCall,
+        attributes: {
+          [GEN_AI_AGENT_NAME]: this.definition.name,
+          [GEN_AI_AGENT_DESCRIPTION]: this.definition.description,
+        },
+      },
+      async ({ metadata }) => {
+        metadata.input = this.params;
+        const result = await invocation.execute(signal, updateOutput);
+        metadata.output = result;
+        return result;
+      },
+    );
   }
 
   private withUserHints(agentArgs: AgentInputs): AgentInputs {