diff --git a/core/src/main/java/com/google/adk/tools/mcp/McpAsyncToolset.java b/core/src/main/java/com/google/adk/tools/mcp/McpAsyncToolset.java
index 73af9cc6a..bcc786d69 100644
--- a/core/src/main/java/com/google/adk/tools/mcp/McpAsyncToolset.java
+++ b/core/src/main/java/com/google/adk/tools/mcp/McpAsyncToolset.java
@@ -22,6 +22,8 @@
 import com.google.adk.tools.BaseTool;
 import com.google.adk.tools.BaseToolset;
 import com.google.adk.tools.NamedToolPredicate;
+import com.google.adk.tools.ToolPredicate;
+import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import io.modelcontextprotocol.client.McpAsyncClient;
@@ -32,8 +34,8 @@
 import java.time.Duration;
 import java.util.List;
 import java.util.Objects;
-import java.util.Optional;
 import java.util.concurrent.atomic.AtomicReference;
+import javax.annotation.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import reactor.core.publisher.Mono;
@@ -59,14 +61,14 @@ public class McpAsyncToolset implements BaseToolset {
 
   private final McpSessionManager mcpSessionManager;
   private final ObjectMapper objectMapper;
-  private final Optional<Object> toolFilter;
+  private final @Nullable Object toolFilter;
   private final AtomicReference<Mono<List<McpAsyncTool>>> mcpTools = new AtomicReference<>();
 
   /** Builder for McpAsyncToolset */
   public static class Builder {
     private Object connectionParams = null;
     private ObjectMapper objectMapper = null;
-    private Optional<Object> toolFilter = null;
+    private @Nullable Object toolFilter = null;
 
     @CanIgnoreReturnValue
     public Builder connectionParams(ServerParameters connectionParams) {
@@ -87,14 +89,14 @@ public Builder objectMapper(ObjectMapper objectMapper) {
     }
 
     @CanIgnoreReturnValue
-    public Builder toolFilter(Optional<Object> toolFilter) {
-      this.toolFilter = toolFilter;
+    public Builder toolFilter(List<String> toolNames) {
+      this.toolFilter = new NamedToolPredicate(Preconditions.checkNotNull(toolNames));
       return this;
     }
 
     @CanIgnoreReturnValue
-    public Builder toolFilter(List<String> toolNames) {
-      this.toolFilter = Optional.of(new NamedToolPredicate(toolNames));
+    public Builder toolFilter(@Nullable ToolPredicate toolPredicate) {
+      this.toolFilter = toolPredicate;
       return this;
     }
 
@@ -118,12 +120,12 @@ public McpAsyncToolset build() {
    *
    * @param connectionParams The SSE connection parameters to the MCP server.
    * @param objectMapper An ObjectMapper instance for parsing schemas.
-   * @param toolFilter An Optional containing either a ToolPredicate or a List of tool names.
+   * @param toolFilter Either a ToolPredicate or a List of tool names.
    */
-  public McpAsyncToolset(
+  McpAsyncToolset(
       SseServerParameters connectionParams,
       ObjectMapper objectMapper,
-      Optional<Object> toolFilter) {
+      @Nullable Object toolFilter) {
     Objects.requireNonNull(connectionParams);
     Objects.requireNonNull(objectMapper);
     this.objectMapper = objectMapper;
@@ -136,10 +138,10 @@ public McpAsyncToolset(
    *
    * @param connectionParams The local server connection parameters to the MCP server.
    * @param objectMapper An ObjectMapper instance for parsing schemas.
-   * @param toolFilter An Optional containing either a ToolPredicate or a List of tool names.
+   * @param toolFilter Either a ToolPredicate or a List of tool names or null.
    */
-  public McpAsyncToolset(
-      ServerParameters connectionParams, ObjectMapper objectMapper, Optional<Object> toolFilter) {
+  McpAsyncToolset(
+      ServerParameters connectionParams, ObjectMapper objectMapper, @Nullable Object toolFilter) {
     Objects.requireNonNull(connectionParams);
     Objects.requireNonNull(objectMapper);
     this.objectMapper = objectMapper;
@@ -147,22 +149,6 @@ public McpAsyncToolset(
     this.toolFilter = toolFilter;
   }
 
-  /**
-   * Initializes the McpAsyncToolset with a provided McpSessionManager.
-   *
-   * @param mcpSessionManager The session manager for MCP connections.
-   * @param objectMapper An ObjectMapper instance for parsing schemas.
-   * @param toolFilter An Optional containing either a ToolPredicate or a List of tool names.
-   */
-  public McpAsyncToolset(
-      McpSessionManager mcpSessionManager, ObjectMapper objectMapper, Optional<Object> toolFilter) {
-    Objects.requireNonNull(mcpSessionManager);
-    Objects.requireNonNull(objectMapper);
-    this.objectMapper = objectMapper;
-    this.mcpSessionManager = mcpSessionManager;
-    this.toolFilter = toolFilter;
-  }
-
   @Override
   public Flowable<BaseTool> getTools(ReadonlyContext readonlyContext) {
     return Maybe.defer(() -> Maybe.fromCompletionStage(this.initAndGetTools().toFuture()))
@@ -170,7 +156,7 @@ public Flowable<BaseTool> getTools(ReadonlyContext readonlyContext) {
         .map(
             tools ->
                 tools.stream()
-                    .filter(tool -> isToolSelected(tool, toolFilter.orElse(null), readonlyContext))
+                    .filter(tool -> isToolSelected(tool, toolFilter, readonlyContext))
                     .toList())
         .onErrorResumeNext(
             err -> {