feat: Updating the Tracing implementation and updating BaseAgent.runLive

This update should make the java tracing consistent with Python ADK:

1.  **`BaseAgent.java`**:
    *   The `runAsync` and `runLive` methods have been modified to create the `InvocationContext` before starting the tracing span.
    *   The span name for agent invocations has been changed from `"agent_run [<agent name>]"` to `"invoke_agent <agent name>"`.
    *   A new `Tracing.traceAgentInvocation` method is now called to add initial tracing attributes for the agent invocation.
    *   In `runLive`, the `runLiveImpl` execution is now wrapped with calls to `beforeAgentCallback` and `afterAgentCallback` to ensure proper tracing of these lifecycle events.

2.  **`Tracing.java`**:
    *   The OpenTelemetry tracer name has been updated from `"com.google.adk"` to `"gcp.vertex.agent"`.
    *   A new `traceAgentInvocation` method has been added to set standard attributes for agent invocation spans, including `gen_ai.operation.name`, `gen_ai.agent.description`, `gen_ai.agent.name`, and `gen_ai.conversation.id`.
    *   Attribute keys used in `traceToolCall`, `traceToolResponse`, `traceCallLlm`, and `traceSendData` have been updated to use the `"gcp.vertex.agent."` prefix instead of `"adk."` or `"com.google.adk"`.
    *   The serialization of message content (like tool call arguments, tool responses, and data) is now guarded by the `CAPTURE_MESSAGE_CONTENT_IN_SPANS` flag. When disabled, empty JSON objects are recorded instead.
    *   `traceToolResponse` now includes logic to extract and trace the `tool_call.id` and the tool response content from `FunctionResponse` objects.
    *   `traceCallLlm` now captures additional LLM request and response details, such as `gen_ai.request.top_p`, `gen_ai.request.max_tokens`, `gen_ai.usage.input_tokens`, `gen_ai.usage.output_tokens`, and `gen_ai.response.finish_reasons`.

PiperOrigin-RevId: 867888690

Author: google-genai-bot

core/src/main/java/com/google/adk/agents/BaseAgent.java

@@ -304,15 +304,12 @@ public Flowable<Event> runAsync(InvocationContext parentContext) {
     Tracer tracer = Tracing.getTracer();
     return Flowable.defer(
         () -> {
+          InvocationContext invocationContext = createInvocationContext(parentContext);
           Span span =
-              tracer
-                  .spanBuilder("agent_run [" + name() + "]")
-                  .setParent(Context.current())
-                  .startSpan();
+              tracer.spanBuilder("invoke_agent " + name()).setParent(Context.current()).startSpan();
+          Tracing.traceAgentInvocation(span, name(), description(), invocationContext);
           Context spanContext = Context.current().with(span);
 
-          InvocationContext invocationContext = createInvocationContext(parentContext);
-
           return Tracing.traceFlowable(
               spanContext,
               span,
@@ -443,16 +440,41 @@ public Flowable<Event> runLive(InvocationContext parentContext) {
     Tracer tracer = Tracing.getTracer();
     return Flowable.defer(
         () -> {
+          InvocationContext invocationContext = createInvocationContext(parentContext);
           Span span =
-              tracer
-                  .spanBuilder("agent_run [" + name() + "]")
-                  .setParent(Context.current())
-                  .startSpan();
+              tracer.spanBuilder("invoke_agent " + name()).setParent(Context.current()).startSpan();
+          Tracing.traceAgentInvocation(span, name(), description(), invocationContext);
           Context spanContext = Context.current().with(span);
 
-          InvocationContext invocationContext = createInvocationContext(parentContext);
+          return Tracing.traceFlowable(
+              spanContext,
+              span,
+              () ->
+                  callCallback(
+                          beforeCallbacksToFunctions(
+                              invocationContext.pluginManager(), beforeAgentCallback),
+                          invocationContext)
+                      .flatMapPublisher(
+                          beforeEventOpt -> {
+                            if (invocationContext.endInvocation()) {
+                              return Flowable.fromOptional(beforeEventOpt);
+                            }
+
+                            Flowable<Event> beforeEvents = Flowable.fromOptional(beforeEventOpt);
+                            Flowable<Event> mainEvents =
+                                Flowable.defer(() -> runLiveImpl(invocationContext));
+                            Flowable<Event> afterEvents =
+                                Flowable.defer(
+                                    () ->
+                                        callCallback(
+                                                afterCallbacksToFunctions(
+                                                    invocationContext.pluginManager(),
+                                                    afterAgentCallback),
+                                                invocationContext)
+                                            .flatMapPublisher(Flowable::fromOptional));
 
-          return Tracing.traceFlowable(spanContext, span, () -> runLiveImpl(invocationContext));
+                            return Flowable.concat(beforeEvents, mainEvents, afterEvents);
+                          }));
         });
   }
 

core/src/main/java/com/google/adk/flows/llmflows/Functions.java

@@ -181,7 +181,7 @@ public static Maybe<Event> handleFunctionCalls(
                 Span mergedSpan =
                     tracer.spanBuilder("tool_response").setParent(Context.current()).startSpan();
                 try (Scope scope = mergedSpan.makeCurrent()) {
-                  Tracing.traceToolResponse(invocationContext, mergedEvent.id(), mergedEvent);
+                  Tracing.traceToolResponse(mergedEvent.id(), mergedEvent);
                 } finally {
                   mergedSpan.end();
                 }
@@ -571,7 +571,8 @@ private static Maybe<Map<String, Object>> callTool(
                   .setParent(parentContext)
                   .startSpan();
           try (Scope scope = span.makeCurrent()) {
-            Tracing.traceToolCall(args);
+            Tracing.traceToolCall(
+                tool.name(), tool.description(), tool.getClass().getSimpleName(), args);
             return tool.runAsync(args, toolContext)
                 .toMaybe()
                 .doOnError(span::recordException)
@@ -620,7 +621,7 @@ private static Event buildResponseEvent(
               .content(Content.builder().role("user").parts(partFunctionResponse).build())
               .actions(toolContext.eventActions())
               .build();
-      Tracing.traceToolResponse(invocationContext, event.id(), event);
+      Tracing.traceToolResponse(event.id(), event);
       return event;
     } finally {
       span.end();