diff --git a/core/src/main/java/com/google/adk/tools/AgentTool.java b/core/src/main/java/com/google/adk/tools/AgentTool.java
index 66d4a2700..7f74ab780 100644
--- a/core/src/main/java/com/google/adk/tools/AgentTool.java
+++ b/core/src/main/java/com/google/adk/tools/AgentTool.java
@@ -16,6 +16,8 @@
 
 package com.google.adk.tools;
 
+import static org.apache.commons.lang3.StringUtils.isNotBlank;
+
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.google.adk.JsonBaseModel;
@@ -131,8 +133,11 @@ private Optional<Schema> getOutputSchema(BaseAgent agent) {
 
   @Override
   public Optional<FunctionDeclaration> declaration() {
+
+    String desc = isNotBlank(this.description()) ? this.description() : this.name();
+
     FunctionDeclaration.Builder builder =
-        FunctionDeclaration.builder().description(this.description()).name(this.name());
+        FunctionDeclaration.builder().description(desc).name(this.name());
 
     Optional<Schema> agentInputSchema = getInputSchema(agent);
 
diff --git a/core/src/test/java/com/google/adk/tools/AgentToolTest.java b/core/src/test/java/com/google/adk/tools/AgentToolTest.java
index b37db6611..2178126b7 100644
--- a/core/src/test/java/com/google/adk/tools/AgentToolTest.java
+++ b/core/src/test/java/com/google/adk/tools/AgentToolTest.java
@@ -43,6 +43,7 @@
 import io.reactivex.rxjava3.core.Flowable;
 import io.reactivex.rxjava3.core.Maybe;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.atomic.AtomicBoolean;
 import org.junit.Before;
 import org.junit.Test;
@@ -882,4 +883,20 @@ private ToolContext createToolContext(BaseAgent agent) {
                 .build())
         .build();
   }
+
+  @Test
+  public void declaration_withNullDescription_fallsBackToName() {
+    // Create an agent with a name but NO description
+    LlmAgent testAgent =
+        LlmAgent.builder()
+            .name("TestAgent")
+            // .description() is intentionally left out
+            .build();
+
+    AgentTool tool = AgentTool.create(testAgent);
+    Optional<FunctionDeclaration> declaration = tool.declaration();
+    assertThat(declaration.isPresent());
+    assertThat(declaration.get().name().get()).isEqualTo("TestAgent");
+    assertThat(declaration.get().description().get()).isEqualTo("TestAgent");
+  }
 }