fix: Relaxing constraints for output schema

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

@@ -594,40 +594,6 @@ protected void validate() {
           this.disallowTransferToParent != null && this.disallowTransferToParent;
       this.disallowTransferToPeers =
           this.disallowTransferToPeers != null && this.disallowTransferToPeers;
-
-      if (this.outputSchema != null) {
-        if (!this.disallowTransferToParent || !this.disallowTransferToPeers) {
-          logger.warn(
-              "Invalid config for agent {}: outputSchema cannot co-exist with agent transfer"
-                  + " configurations. Setting disallowTransferToParent=true and"
-                  + " disallowTransferToPeers=true.",
-              this.name);
-          this.disallowTransferToParent = true;
-          this.disallowTransferToPeers = true;
-        }
-
-        if (this.subAgents != null && !this.subAgents.isEmpty()) {
-          throw new IllegalArgumentException(
-              "Invalid config for agent "
-                  + this.name
-                  + ": if outputSchema is set, subAgents must be empty to disable agent"
-                  + " transfer.");
-        }
-        if (this.toolsUnion != null && !this.toolsUnion.isEmpty()) {
-          boolean hasOtherTools =
-              this.toolsUnion.stream()
-                  .anyMatch(
-                      tool ->
-                          !(tool instanceof BaseTool baseTool)
-                              || !baseTool.name().equals("example_tool"));
-          if (hasOtherTools) {
-            throw new IllegalArgumentException(
-                "Invalid config for agent "
-                    + this.name
-                    + ": if outputSchema is set, tools must be empty.");
-          }
-        }
-      }
     }
 
     @Override

core/src/test/java/com/google/adk/agents/LlmAgentTest.java

@@ -26,7 +26,6 @@
 import static com.google.common.collect.Iterables.getOnlyElement;
 import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertThrows;
 
 import com.google.adk.agents.Callbacks.AfterModelCallback;
 import com.google.adk.agents.Callbacks.AfterToolCallback;
@@ -52,9 +51,9 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.genai.types.Content;
-import com.google.genai.types.FunctionDeclaration;
 import com.google.genai.types.Part;
 import com.google.genai.types.Schema;
+import com.google.genai.types.Type;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.Tracer;
 import io.opentelemetry.sdk.testing.junit4.OpenTelemetryRule;
@@ -63,7 +62,6 @@
 import io.reactivex.rxjava3.core.Maybe;
 import io.reactivex.rxjava3.core.Single;
 import java.util.List;
-import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicBoolean;
 import org.junit.After;
@@ -80,6 +78,12 @@ public final class LlmAgentTest {
 
   private Tracer originalTracer;
 
+  private static class PersonSchema {
+    public String name;
+    public int age;
+    public String city;
+  }
+
   @Before
   public void setup() {
     this.originalTracer = Tracing.getTracer();
@@ -213,75 +217,6 @@ public void run_withToolsAndMaxSteps_stopsAfterMaxSteps() {
     assertEqualIgnoringFunctionIds(events.get(3).content().get(), expectedFunctionResponseContent);
   }
 
-  @Test
-  public void build_withOutputSchemaAndTools_throwsIllegalArgumentException() {
-    BaseTool tool =
-        new BaseTool("test_tool", "test_description") {
-          @Override
-          public Optional<FunctionDeclaration> declaration() {
-            return Optional.empty();
-          }
-        };
-
-    Schema outputSchema =
-        Schema.builder()
-            .type("OBJECT")
-            .properties(ImmutableMap.of("status", Schema.builder().type("STRING").build()))
-            .required(ImmutableList.of("status"))
-            .build();
-
-    // Expecting an IllegalArgumentException when building the agent
-    IllegalArgumentException exception =
-        assertThrows(
-            IllegalArgumentException.class,
-            () ->
-                LlmAgent.builder() // Use the agent builder directly
-                    .name("agent with invalid tool config")
-                    .outputSchema(outputSchema) // Set the output schema
-                    .tools(ImmutableList.of(tool)) // Set tools (this should cause the error)
-                    .build()); // Attempt to build the agent
-
-    assertThat(exception)
-        .hasMessageThat()
-        .contains(
-            "Invalid config for agent agent with invalid tool config: if outputSchema is set, tools"
-                + " must be empty");
-  }
-
-  @Test
-  public void build_withOutputSchemaAndSubAgents_throwsIllegalArgumentException() {
-    ImmutableList<BaseAgent> subAgents =
-        ImmutableList.of(
-            createTestAgentBuilder(createTestLlm(LlmResponse.builder().build()))
-                .name("test_sub_agent")
-                .description("test_sub_agent_description")
-                .build());
-
-    Schema outputSchema =
-        Schema.builder()
-            .type("OBJECT")
-            .properties(ImmutableMap.of("status", Schema.builder().type("STRING").build()))
-            .required(ImmutableList.of("status"))
-            .build();
-
-    // Expecting an IllegalArgumentException when building the agent
-    IllegalArgumentException exception =
-        assertThrows(
-            IllegalArgumentException.class,
-            () ->
-                LlmAgent.builder() // Use the agent builder directly
-                    .name("agent with invalid tool config")
-                    .outputSchema(outputSchema) // Set the output schema
-                    .subAgents(subAgents) // Set subAgents (this should cause the error)
-                    .build()); // Attempt to build the agent
-
-    assertThat(exception)
-        .hasMessageThat()
-        .contains(
-            "Invalid config for agent agent with invalid tool config: if outputSchema is set,"
-                + " subAgents must be empty to disable agent transfer.");
-  }
-
   @Test
   public void testBuild_withNullInstruction_setsInstructionToEmptyString() {
     LlmAgent agent =
@@ -645,6 +580,31 @@ public void runAsync_withSubAgents_createsSpans() throws InterruptedException {
     assertThat(llmSpans).hasSize(2); // One for main agent, one for sub agent
   }
 
+  @Test
+  public void run_outputSchemaWithTools_allowed() {
+    Schema personShema =
+        Schema.builder()
+            .type(Type.Known.OBJECT)
+            .properties(
+                ImmutableMap.of(
+                    "name", Schema.builder().type(Type.Known.STRING).build(),
+                    "age", Schema.builder().type(Type.Known.INTEGER).build(),
+                    "city", Schema.builder().type(Type.Known.STRING).build()))
+            .build();
+    LlmAgent agent =
+        createTestAgentBuilder(createTestLlm(LlmResponse.builder().build()))
+            .outputSchema(personShema)
+            .tools(new EchoTool())
+            .build();
+    assertThat(agent.outputSchema()).hasValue(personShema);
+    assertThat(
+            agent
+                .canonicalTools(new ReadonlyContext(createInvocationContext(agent)))
+                .count()
+                .blockingGet())
+        .isEqualTo(1);
+  }
+
   private List<SpanData> findSpansByName(List<SpanData> spans, String name) {
     return spans.stream().filter(s -> s.getName().equals(name)).toList();
   }