diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 73d3293b9..6180eb92e 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-    ".": "1.4.0"
+    ".": "1.5.0"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 970000c5b..6326a1382 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## [1.5.0](https://github.com/google/adk-java/compare/v1.4.0...v1.5.0) (2026-06-01)
+
+
+### Features
+
+* support optional types in function tool parameters ([9a06dd3](https://github.com/google/adk-java/commit/9a06dd34dc823af54d3ea229a0d141768593d376))
+
+
+### Bug Fixes
+
+* SkillMdPath should be public ([29d3203](https://github.com/google/adk-java/commit/29d3203a6fab4268a3588acddde7b59c73f7b624))
+
 ## [1.4.0](https://github.com/google/adk-java/compare/v1.3.0...v1.4.0) (2026-05-29)
 
 
diff --git a/README.md b/README.md
index 8d337d6a7..97cdf1910 100644
--- a/README.md
+++ b/README.md
@@ -50,13 +50,13 @@ If you're using Maven, add the following to your dependencies:
 <dependency>
   <groupId>com.google.adk</groupId>
   <artifactId>google-adk</artifactId>
-  <version>1.4.0</version>
+  <version>1.5.0</version>
 </dependency>
 <!-- Dev UI -->
 <dependency>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-dev</artifactId>
-    <version>1.4.0</version>
+    <version>1.5.0</version>
 </dependency>
 ```
 
diff --git a/a2a/pom.xml b/a2a/pom.xml
index cb90a89cf..5b27e15ab 100644
--- a/a2a/pom.xml
+++ b/a2a/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-parent</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
   </parent>
 
   <artifactId>google-adk-a2a</artifactId>
diff --git a/contrib/firestore-session-service/pom.xml b/contrib/firestore-session-service/pom.xml
index 6abf2f217..99b14abe2 100644
--- a/contrib/firestore-session-service/pom.xml
+++ b/contrib/firestore-session-service/pom.xml
@@ -20,7 +20,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-parent</artifactId>
-        <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>../../pom.xml</relativePath>
     </parent>
 
diff --git a/contrib/langchain4j/pom.xml b/contrib/langchain4j/pom.xml
index 84a9ed89d..8ab7a7143 100644
--- a/contrib/langchain4j/pom.xml
+++ b/contrib/langchain4j/pom.xml
@@ -20,7 +20,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-parent</artifactId>
-        <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>../../pom.xml</relativePath>
     </parent>
 
diff --git a/contrib/planners/pom.xml b/contrib/planners/pom.xml
index 6be1ee680..3680ab46b 100644
--- a/contrib/planners/pom.xml
+++ b/contrib/planners/pom.xml
@@ -20,7 +20,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-parent</artifactId>
-        <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>../../pom.xml</relativePath>
     </parent>
 
diff --git a/contrib/samples/a2a_basic/pom.xml b/contrib/samples/a2a_basic/pom.xml
index 57bb0ac5f..053d7a042 100644
--- a/contrib/samples/a2a_basic/pom.xml
+++ b/contrib/samples/a2a_basic/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-samples</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
     <relativePath>..</relativePath>
   </parent>
 
diff --git a/contrib/samples/a2a_server/pom.xml b/contrib/samples/a2a_server/pom.xml
index dcaa164fd..43f374468 100644
--- a/contrib/samples/a2a_server/pom.xml
+++ b/contrib/samples/a2a_server/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-samples</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
     <relativePath>..</relativePath>
   </parent>
 
diff --git a/contrib/samples/configagent/pom.xml b/contrib/samples/configagent/pom.xml
index 7642464ef..fd40ddded 100644
--- a/contrib/samples/configagent/pom.xml
+++ b/contrib/samples/configagent/pom.xml
@@ -5,7 +5,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-samples</artifactId>
-        <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>..</relativePath>
     </parent>
 
diff --git a/contrib/samples/helloworld/pom.xml b/contrib/samples/helloworld/pom.xml
index 5010e3aa0..9b943e6b2 100644
--- a/contrib/samples/helloworld/pom.xml
+++ b/contrib/samples/helloworld/pom.xml
@@ -20,7 +20,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-samples</artifactId>
-        <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>..</relativePath>
     </parent>
 
diff --git a/contrib/samples/mcpfilesystem/pom.xml b/contrib/samples/mcpfilesystem/pom.xml
index 4f5de99b7..8546c55d5 100644
--- a/contrib/samples/mcpfilesystem/pom.xml
+++ b/contrib/samples/mcpfilesystem/pom.xml
@@ -20,7 +20,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-parent</artifactId>
-        <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>../../..</relativePath>
     </parent>
 
diff --git a/contrib/samples/pom.xml b/contrib/samples/pom.xml
index 0336dfbba..033197b10 100644
--- a/contrib/samples/pom.xml
+++ b/contrib/samples/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-parent</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
     <relativePath>../..</relativePath>
   </parent>
 
diff --git a/contrib/spring-ai/pom.xml b/contrib/spring-ai/pom.xml
index e079d8cc9..a63d2db1e 100644
--- a/contrib/spring-ai/pom.xml
+++ b/contrib/spring-ai/pom.xml
@@ -20,7 +20,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-parent</artifactId>
-        <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>../../pom.xml</relativePath>
     </parent>
 
diff --git a/core/pom.xml b/core/pom.xml
index f4dc6375c..796404772 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-parent</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
   </parent>
 
   <artifactId>google-adk</artifactId>
diff --git a/core/src/main/java/com/google/adk/Version.java b/core/src/main/java/com/google/adk/Version.java
index 92dc4a50a..21f774b72 100644
--- a/core/src/main/java/com/google/adk/Version.java
+++ b/core/src/main/java/com/google/adk/Version.java
@@ -22,7 +22,7 @@
  */
 public final class Version {
   // Don't touch this, release-please should keep it up to date.
-  public static final String JAVA_ADK_VERSION = "1.4.0"; // x-release-please-released-version
+  public static final String JAVA_ADK_VERSION = "1.5.0"; // x-release-please-released-version
 
   private Version() {}
 }
diff --git a/dev/pom.xml b/dev/pom.xml
index fb5443981..cf790f005 100644
--- a/dev/pom.xml
+++ b/dev/pom.xml
@@ -18,7 +18,7 @@
   <parent>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-parent</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
   </parent>
 
   <artifactId>google-adk-dev</artifactId>
diff --git a/maven_plugin/examples/custom_tools/pom.xml b/maven_plugin/examples/custom_tools/pom.xml
index 47505f408..4cf393f4e 100644
--- a/maven_plugin/examples/custom_tools/pom.xml
+++ b/maven_plugin/examples/custom_tools/pom.xml
@@ -4,7 +4,7 @@
 
     <groupId>com.example</groupId>
     <artifactId>custom-tools-example</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
     <packaging>jar</packaging>
 
     <name>ADK Custom Tools Example</name>
diff --git a/maven_plugin/examples/simple-agent/pom.xml b/maven_plugin/examples/simple-agent/pom.xml
index d923e3e59..548bdbc1c 100644
--- a/maven_plugin/examples/simple-agent/pom.xml
+++ b/maven_plugin/examples/simple-agent/pom.xml
@@ -4,7 +4,7 @@
 
     <groupId>com.example</groupId>
     <artifactId>simple-adk-agent</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
     <packaging>jar</packaging>
 
     <name>Simple ADK Agent Example</name>
diff --git a/maven_plugin/pom.xml b/maven_plugin/pom.xml
index d737d8133..539b68961 100644
--- a/maven_plugin/pom.xml
+++ b/maven_plugin/pom.xml
@@ -5,7 +5,7 @@
     <parent>
         <groupId>com.google.adk</groupId>
         <artifactId>google-adk-parent</artifactId>
-        <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
         <relativePath>../pom.xml</relativePath>
     </parent>
 
diff --git a/pom.xml b/pom.xml
index 4784a793c..80c8d6430 100644
--- a/pom.xml
+++ b/pom.xml
@@ -17,7 +17,7 @@
 
   <groupId>com.google.adk</groupId>
   <artifactId>google-adk-parent</artifactId>
-  <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+  <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
   <packaging>pom</packaging>
 
   <name>Google Agent Development Kit Maven Parent POM</name>
diff --git a/tutorials/city-time-weather/pom.xml b/tutorials/city-time-weather/pom.xml
index 6954aa44d..d0bcaa16e 100644
--- a/tutorials/city-time-weather/pom.xml
+++ b/tutorials/city-time-weather/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-parent</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
diff --git a/tutorials/live-audio-single-agent/pom.xml b/tutorials/live-audio-single-agent/pom.xml
index 16c1a2750..02e1e49c4 100644
--- a/tutorials/live-audio-single-agent/pom.xml
+++ b/tutorials/live-audio-single-agent/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>com.google.adk</groupId>
     <artifactId>google-adk-parent</artifactId>
-    <version>1.4.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+    <version>1.5.0</version><!-- {x-version-update:google-adk:current} -->
     <relativePath>../../pom.xml</relativePath>
   </parent>