fix: Update AgentTool to drop thought parts from response

Before we silently assumed that the last event had a single part with the text in it. Now we return all the non-thought text.

PiperOrigin-RevId: 825848406

Author: Poggecci

core/src/main/java/com/google/adk/tools/AgentTool.java

@@ -120,12 +120,7 @@ public Single<Map<String, Object>> runAsync(Map<String, Object> args, ToolContex
                 return ImmutableMap.of();
               }
               Event lastEvent = optionalLastEvent.get();
-              Optional<String> outputText =
-                  lastEvent
-                      .content()
-                      .flatMap(Content::parts)
-                      .filter(parts -> !parts.isEmpty())
-                      .flatMap(parts -> parts.get(0).text());
+              Optional<String> outputText = lastEvent.content().map(Content::text);
 
               if (outputText.isEmpty()) {
                 return ImmutableMap.of();

core/src/test/java/com/google/adk/tools/AgentToolTest.java

@@ -227,7 +227,7 @@ public void call_withInputAndOutputSchema_successful() throws Exception {
   }
 
   @Test
-  public void call_withoutSchema_returnsFirstTextPartFromLastEvent() throws Exception {
+  public void call_withoutSchema_returnsConcatenatedTextFromLastEvent() throws Exception {
     LlmAgent testAgent =
         createTestAgentBuilder(
                 createTestLlm(
@@ -240,8 +240,8 @@ public void call_withoutSchema_returnsFirstTextPartFromLastEvent() throws Except
                         LlmResponse.builder()
                             .content(
                                 Content.fromParts(
-                                    Part.fromText("First text part is returned"),
-                                    Part.fromText("This should be ignored")))
+                                    Part.fromText("First text part. "),
+                                    Part.fromText("Second text part.")))
                             .build())))
             .name("agent name")
             .description("agent description")
@@ -252,7 +252,31 @@ public void call_withoutSchema_returnsFirstTextPartFromLastEvent() throws Except
     Map<String, Object> result =
         agentTool.runAsync(ImmutableMap.of("request", "magic"), toolContext).blockingGet();
 
-    assertThat(result).containsExactly("result", "First text part is returned");
+    assertThat(result).containsExactly("result", "First text part. Second text part.");
+  }
+
+  @Test
+  public void call_withThoughts_returnsOnlyNonThoughtText() throws Exception {
+    TestLlm testLlm =
+        createTestLlm(
+            LlmResponse.builder()
+                .content(
+                    Content.builder()
+                        .parts(
+                            Part.fromText("Non-thought text 1. "),
+                            Part.builder().text("This is a thought.").thought(true).build(),
+                            Part.fromText("Non-thought text 2."))
+                        .build())
+                .build());
+    LlmAgent testAgent =
+        createTestAgentBuilder(testLlm).name("agent name").description("agent description").build();
+    AgentTool agentTool = AgentTool.create(testAgent);
+    ToolContext toolContext = createToolContext(testAgent);
+
+    Map<String, Object> result =
+        agentTool.runAsync(ImmutableMap.of("request", "test"), toolContext).blockingGet();
+
+    assertThat(result).containsExactly("result", "Non-thought text 1. Non-thought text 2.");
   }
 
   @Test