feat: add fromConfig method to LongRunningFunctionTool

The config's `func` parameter is interpreted as a name of a FuncTool
registered elsewhere, that the LongRunningFunction tool is wrapping

PiperOrigin-RevId: 845734852

Author: google-genai-bot

core/src/main/java/com/google/adk/tools/FunctionTool.java

@@ -185,6 +185,17 @@ public Method func() {
     return func;
   }
 
+  /** Returns the underlying function's {@link Object} instance if present. */
+  @Nullable
+  Object instance() {
+    return instance;
+  }
+
+  /** Returns whether the function requires confirmation */
+  boolean requireConfirmation() {
+    return requireConfirmation;
+  }
+
   /** Returns true if the wrapped function returns a Flowable and can be used for streaming. */
   public boolean isStreaming() {
     Type returnType = func.getGenericReturnType();

core/src/main/java/com/google/adk/tools/LongRunningFunctionTool.java

@@ -16,6 +16,8 @@
 
 package com.google.adk.tools;
 
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.google.adk.utils.ComponentRegistry;
 import java.lang.reflect.Method;
 import javax.annotation.Nullable;
 
@@ -70,6 +72,11 @@ public static LongRunningFunctionTool create(
     return new LongRunningFunctionTool(instance, method, requireConfirmation);
   }
 
+  /** Creates a LongRunningFunctionTool from a FunctionTool. */
+  public static LongRunningFunctionTool create(FunctionTool tool) {
+    return create(tool.instance(), tool.func(), tool.requireConfirmation());
+  }
+
   private LongRunningFunctionTool(Method func, boolean requireConfirmation) {
     super(null, func, /* isLongRunning= */ true, requireConfirmation);
   }
@@ -78,4 +85,25 @@ private LongRunningFunctionTool(
       @Nullable Object instance, Method func, boolean requireConfirmation) {
     super(instance, func, /* isLongRunning= */ true, requireConfirmation);
   }
+
+  public static LongRunningFunctionTool fromConfig(ToolArgsConfig config, String configAbsPath) {
+    String funcName =
+        config
+            .getOrEmpty("func", new TypeReference<String>() {})
+            .orElseThrow(
+                () ->
+                    new IllegalArgumentException("\"func\" argument should be name of a function"));
+
+    FunctionTool funcTool =
+        ComponentRegistry.getInstance()
+            .get(funcName, FunctionTool.class)
+            .orElseThrow(
+                () ->
+                    new IllegalArgumentException(
+                        String.format(
+                            "failed to find FunctionTool \"%s\" in the ComponentRegistry",
+                            funcName)));
+
+    return create(funcTool);
+  }
 }

core/src/main/java/com/google/adk/utils/ComponentRegistry.java

@@ -32,6 +32,7 @@
 import com.google.adk.tools.ExitLoopTool;
 import com.google.adk.tools.GoogleSearchTool;
 import com.google.adk.tools.LoadArtifactsTool;
+import com.google.adk.tools.LongRunningFunctionTool;
 import com.google.adk.tools.UrlContextTool;
 import com.google.adk.tools.mcp.McpToolset;
 import java.util.Map;
@@ -110,6 +111,7 @@ private void initializePreWiredEntries() {
     registerAdkToolInstance("url_context", UrlContextTool.INSTANCE);
 
     registerAdkToolClass(AgentTool.class);
+    registerAdkToolClass(LongRunningFunctionTool.class);
 
     registerAdkToolsetClass(McpToolset.class);
     // TODO: add all python tools that also exist in Java.

core/src/test/java/com/google/adk/tools/LongRunningFunctionToolTest.java

@@ -1,6 +1,7 @@
 package com.google.adk.tools;
 
 import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
 
 import com.google.adk.agents.LlmAgent;
 import com.google.adk.artifacts.InMemoryArtifactService;
@@ -13,6 +14,8 @@
 import com.google.adk.sessions.InMemorySessionService;
 import com.google.adk.sessions.Session;
 import com.google.adk.testing.TestLlm;
+import com.google.adk.tools.BaseTool.ToolArgsConfig;
+import com.google.adk.utils.ComponentRegistry;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.errorprone.annotations.Keep;
@@ -92,6 +95,51 @@ public void asyncFunction_handlesPendingAndResults() throws Exception {
     assertThat(TestFunctions.functionCalledCount.get()).isEqualTo(1);
   }
 
+  @Test
+  public void fromConfig_validConfig_createsTool() throws Exception {
+    // Register a FunctionTool to be retrieved by fromConfig
+    FunctionTool testTool =
+        FunctionTool.create(
+            null, TestFunctions.class.getMethod("increaseByOne", int.class, ToolContext.class));
+    ComponentRegistry.getInstance().register("testFunc", testTool);
+
+    ToolArgsConfig config = new ToolArgsConfig();
+    config.put("func", "testFunc");
+    LongRunningFunctionTool longRunningTool =
+        LongRunningFunctionTool.fromConfig(config, "testPath");
+
+    assertThat(longRunningTool).isNotNull();
+    assertThat(longRunningTool.name()).isEqualTo("increase_by_one");
+  }
+
+  @Test
+  public void fromConfig_missingFunc_throwsException() {
+    ToolArgsConfig config = new ToolArgsConfig();
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> LongRunningFunctionTool.fromConfig(config, "testPath"));
+  }
+
+  @Test
+  public void fromConfig_funcNotString_throwsException() {
+    ToolArgsConfig config = new ToolArgsConfig();
+    config.put("func", 123);
+    assertThrows(
+        IllegalArgumentException.class,
+        () -> LongRunningFunctionTool.fromConfig(config, "testPath"));
+  }
+
+  @Test
+  public void fromConfig_funcNotFound_throwsException() {
+    ToolArgsConfig config = new ToolArgsConfig();
+    config.put("func", "nonExistentFunc");
+    IllegalArgumentException exception =
+        assertThrows(
+            IllegalArgumentException.class,
+            () -> LongRunningFunctionTool.fromConfig(config, "testPath"));
+    assertThat(exception).hasMessageThat().contains("\"nonExistentFunc\"");
+  }
+
   private static class TestFunctions {
     static final AtomicInteger functionCalledCount = new AtomicInteger(0);