diff --git a/core/src/main/java/com/google/adk/agents/BaseAgent.java b/core/src/main/java/com/google/adk/agents/BaseAgent.java
index fc1f0f31e..5dea10434 100644
--- a/core/src/main/java/com/google/adk/agents/BaseAgent.java
+++ b/core/src/main/java/com/google/adk/agents/BaseAgent.java
@@ -185,7 +185,7 @@ public final String name() {
    *
    * @return the description of the agent.
    */
-  public final String description() {
+  public String description() {
     return description;
   }
 
diff --git a/core/src/main/java/com/google/adk/tools/mcp/AbstractMcpTool.java b/core/src/main/java/com/google/adk/tools/mcp/AbstractMcpTool.java
index 86f7a8292..0fcb74846 100644
--- a/core/src/main/java/com/google/adk/tools/mcp/AbstractMcpTool.java
+++ b/core/src/main/java/com/google/adk/tools/mcp/AbstractMcpTool.java
@@ -26,6 +26,7 @@
 import com.google.genai.types.FunctionDeclaration;
 import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
 import io.modelcontextprotocol.spec.McpSchema.Content;
+import io.modelcontextprotocol.spec.McpSchema.JsonSchema;
 import io.modelcontextprotocol.spec.McpSchema.TextContent;
 import io.modelcontextprotocol.spec.McpSchema.Tool;
 import io.modelcontextprotocol.spec.McpSchema.ToolAnnotations;
@@ -86,7 +87,7 @@ public T getMcpSession() {
 
   @Override
   public Optional<FunctionDeclaration> declaration() {
-    Map<String, Object> inputSchema = this.mcpTool.inputSchema();
+    JsonSchema inputSchema = this.mcpTool.inputSchema();
     Map<String, Object> outputSchema = this.mcpTool.outputSchema();
     try {
       return Optional.ofNullable(inputSchema)
diff --git a/core/src/main/java/com/google/adk/tools/mcp/DefaultMcpTransportBuilder.java b/core/src/main/java/com/google/adk/tools/mcp/DefaultMcpTransportBuilder.java
index 086e0867d..1e951dbda 100644
--- a/core/src/main/java/com/google/adk/tools/mcp/DefaultMcpTransportBuilder.java
+++ b/core/src/main/java/com/google/adk/tools/mcp/DefaultMcpTransportBuilder.java
@@ -49,8 +49,8 @@ public McpClientTransport build(Object connectionParams) {
       return HttpClientSseClientTransport.builder(sseServerParams.url())
           .sseEndpoint(
               sseServerParams.sseEndpoint() == null ? "sse" : sseServerParams.sseEndpoint())
-          .httpRequestCustomizer(
-              (builder, method, uri, body, context) ->
+          .customizeRequest(
+              builder ->
                   Optional.ofNullable(sseServerParams.headers())
                       .map(ImmutableMap::entrySet)
                       .stream()
diff --git a/core/src/test/java/com/google/adk/tools/mcp/ConversionUtilsTest.java b/core/src/test/java/com/google/adk/tools/mcp/ConversionUtilsTest.java
index fce0934fd..0b3749269 100644
--- a/core/src/test/java/com/google/adk/tools/mcp/ConversionUtilsTest.java
+++ b/core/src/test/java/com/google/adk/tools/mcp/ConversionUtilsTest.java
@@ -62,7 +62,7 @@ public void adkToMcpToolType_declarationWithParameters_setsInputSchema() {
   }
 
   @Test
-  public void adkToMcpToolType_declarationWithoutParameters_defaultsInputSchema() {
+  public void adkToMcpToolType_declarationWithoutParameters_omitsInputSchema() {
     // A present declaration with no parameters is a valid no-argument tool. Before the fix this
     // threw NoSuchElementException from an unguarded Optional.get() on parameters().
     FunctionDeclaration declaration = FunctionDeclaration.builder().name("noParams").build();
@@ -72,17 +72,17 @@ public void adkToMcpToolType_declarationWithoutParameters_defaultsInputSchema()
 
     assertThat(result.name()).isEqualTo("noParams");
     assertThat(result.description()).isEqualTo("no params");
-    assertThat(result.inputSchema()).containsExactly("type", "object");
+    assertThat(result.inputSchema()).isNull();
   }
 
   @Test
-  public void adkToMcpToolType_noDeclaration_defaultsInputSchema() {
+  public void adkToMcpToolType_noDeclaration_omitsInputSchema() {
     BaseTool tool = new FakeTool("bare", "no declaration", Optional.empty());
 
     McpSchema.Tool result = ConversionUtils.adkToMcpToolType(tool);
 
     assertThat(result.name()).isEqualTo("bare");
     assertThat(result.description()).isEqualTo("no declaration");
-    assertThat(result.inputSchema()).containsExactly("type", "object");
+    assertThat(result.inputSchema()).isNull();
   }
 }
diff --git a/pom.xml b/pom.xml
index 9a689382e..9eff18894 100644
--- a/pom.xml
+++ b/pom.xml
@@ -53,7 +53,7 @@
          cloud libraries. Once they update their otel dependencies we
          can consider updating ours here as well -->
     <otel.version>1.51.0</otel.version>
-    <mcp.version>2.0.0</mcp.version>
+    <mcp.version>1.1.2</mcp.version>
     <errorprone.version>2.47.0</errorprone.version>
     <google.genai.version>1.58.0</google.genai.version>
     <protobuf.version>4.33.5</protobuf.version>