google · copybara-service · Aug 28, 2025 · Aug 28, 2025
diff --git a/src/google/adk/agents/agent_config.py b/src/google/adk/agents/agent_config.py
@@ -14,53 +14,60 @@
 
 from __future__ import annotations
 
+from typing import Annotated
 from typing import Any
+from typing import get_args
 from typing import Union
 
 from pydantic import Discriminator
 from pydantic import RootModel
+from pydantic import Tag
 
 from ..utils.feature_decorator import experimental
-from .base_agent import BaseAgentConfig
+from .base_agent_config import BaseAgentConfig
 from .llm_agent_config import LlmAgentConfig
 from .loop_agent_config import LoopAgentConfig
-from .parallel_agent import ParallelAgentConfig
-from .sequential_agent import SequentialAgentConfig
+from .parallel_agent_config import ParallelAgentConfig
+from .sequential_agent_config import SequentialAgentConfig
 
-# A discriminated union of all possible agent configurations.
-ConfigsUnion = Union[
-    LlmAgentConfig,
-    LoopAgentConfig,
-    ParallelAgentConfig,
-    SequentialAgentConfig,
-    BaseAgentConfig,
-]
+_ADK_AGENT_CLASSES: set[str] = {
+    "LlmAgent",
+    "LoopAgent",
+    "ParallelAgent",
+    "SequentialAgent",
+}
 
 
-def agent_config_discriminator(v: Any):
+def agent_config_discriminator(v: Any) -> str:
+  """Discriminator function that returns the tag name for Pydantic."""
   if isinstance(v, dict):
-    agent_class = v.get("agent_class", "LlmAgent")
-    if agent_class in [
-        "LlmAgent",
-        "LoopAgent",
-        "ParallelAgent",
-        "SequentialAgent",
-    ]:
+    agent_class: str = v.get("agent_class", "LlmAgent")
+
+    # Look up the agent_class in our dynamically built mapping
+    if agent_class in _ADK_AGENT_CLASSES:
       return agent_class
-    else:
-      return "BaseAgent"
+
+    # For non ADK agent classes, use BaseAgent to handle it.
+    return "BaseAgent"
 
   raise ValueError(f"Invalid agent config: {v}")
 
 
+# A discriminated union of all possible agent configurations.
+ConfigsUnion = Annotated[
+    Union[
+        Annotated[LlmAgentConfig, Tag("LlmAgent")],
+        Annotated[LoopAgentConfig, Tag("LoopAgent")],
+        Annotated[ParallelAgentConfig, Tag("ParallelAgent")],
+        Annotated[SequentialAgentConfig, Tag("SequentialAgent")],
+        Annotated[BaseAgentConfig, Tag("BaseAgent")],
+    ],
+    Discriminator(agent_config_discriminator),
+]
+
+
 # Use a RootModel to represent the agent directly at the top level.
 # The `discriminator` is applied to the union within the RootModel.
 @experimental
 class AgentConfig(RootModel[ConfigsUnion]):
   """The config for the YAML schema to create an agent."""
-
-  class Config:
-    # Pydantic v2 requires this for discriminated unions on RootModel
-    # This tells the model to look at the 'agent_class' field of the input
-    # data to decide which model from the `ConfigsUnion` to use.
-    discriminator = Discriminator(agent_config_discriminator)
diff --git a/src/google/adk/agents/config_schemas/AgentConfig.json b/src/google/adk/agents/config_schemas/AgentConfig.json
@@ -681,12 +681,29 @@
     "EnterpriseWebSearch": {
       "additionalProperties": false,
       "description": "Tool to search public web data, powered by Vertex AI Search and Sec4 compliance.",
-      "properties": {},
+      "properties": {
+        "excludeDomains": {
+          "anyOf": [
+            {
+              "items": {
+                "type": "string"
+              },
+              "type": "array"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "default": null,
+          "description": "Optional. List of domains to be excluded from the search results. The default limit is 2000 domains.",
+          "title": "Excludedomains"
+        }
+      },
       "title": "EnterpriseWebSearch",
       "type": "object"
     },
     "Environment": {
-      "description": "Required. The environment being operated.",
+      "description": "The environment being operated.",
       "enum": [
         "ENVIRONMENT_UNSPECIFIED",
         "ENVIRONMENT_BROWSER"
@@ -1475,31 +1492,31 @@
             {
               "$ref": "#/$defs/Content"
             },
+            {
+              "type": "string"
+            },
+            {
+              "$ref": "#/$defs/File"
+            },
+            {
+              "$ref": "#/$defs/Part"
+            },
             {
               "items": {
                 "anyOf": [
                   {
-                    "$ref": "#/$defs/File"
+                    "type": "string"
                   },
                   {
-                    "$ref": "#/$defs/Part"
+                    "$ref": "#/$defs/File"
                   },
                   {
-                    "type": "string"
+                    "$ref": "#/$defs/Part"
                   }
                 ]
               },
               "type": "array"
             },
-            {
-              "$ref": "#/$defs/File"
-            },
-            {
-              "$ref": "#/$defs/Part"
-            },
-            {
-              "type": "string"
-            },
             {
               "type": "null"
             }
@@ -1830,10 +1847,10 @@
         "speechConfig": {
           "anyOf": [
             {
-              "$ref": "#/$defs/SpeechConfig"
+              "type": "string"
             },
             {
-              "type": "string"
+              "$ref": "#/$defs/SpeechConfig"
             },
             {
               "type": "null"
@@ -1999,6 +2016,22 @@
           ],
           "default": null,
           "description": "Optional. Filter search results to a specific time range.\n      If customers set a start time, they must set an end time (and vice versa).\n      "
+        },
+        "excludeDomains": {
+          "anyOf": [
+            {
+              "items": {
+                "type": "string"
+              },
+              "type": "array"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "default": null,
+          "description": "Optional. List of domains to be excluded from the search results.\n      The default limit is 2000 domains.",
+          "title": "Excludedomains"
         }
       },
       "title": "GoogleSearch",
@@ -2356,10 +2389,6 @@
         "agent_class": {
           "default": "LlmAgent",
           "description": "The value is used to uniquely identify the LlmAgent class. If it is empty, it is by default an LlmAgent.",
-          "enum": [
-            "LlmAgent",
-            ""
-          ],
           "title": "Agent Class",
           "type": "string"
         },
@@ -2618,7 +2647,6 @@
       "description": "The config for the YAML schema of a LoopAgent.",
       "properties": {
         "agent_class": {
-          "const": "LoopAgent",
           "default": "LoopAgent",
           "description": "The value is used to uniquely identify the LoopAgent class.",
           "title": "Agent Class",
@@ -2774,7 +2802,6 @@
       "description": "The config for the YAML schema of a ParallelAgent.",
       "properties": {
         "agent_class": {
-          "const": "ParallelAgent",
           "default": "ParallelAgent",
           "description": "The value is used to uniquely identify the ParallelAgent class.",
           "title": "Agent Class",
@@ -3680,7 +3707,6 @@
       "description": "The config for the YAML schema of a SequentialAgent.",
       "properties": {
         "agent_class": {
-          "const": "SequentialAgent",
           "default": "SequentialAgent",
           "description": "The value is used to uniquely identify the SequentialAgent class.",
           "title": "Agent Class",
@@ -4413,29 +4439,29 @@
           "default": null,
           "description": "Optional. Tool to support URL context retrieval."
         },
-        "codeExecution": {
+        "computerUse": {
           "anyOf": [
             {
-              "$ref": "#/$defs/ToolCodeExecution"
+              "$ref": "#/$defs/ToolComputerUse"
             },
             {
               "type": "null"
             }
           ],
           "default": null,
-          "description": "Optional. CodeExecution tool type. Enables the model to execute code as part of generation."
+          "description": "Optional. Tool to support the model interacting directly with the\n      computer. If enabled, it automatically populates computer-use specific\n      Function Declarations."
         },
-        "computerUse": {
+        "codeExecution": {
           "anyOf": [
             {
-              "$ref": "#/$defs/ToolComputerUse"
+              "$ref": "#/$defs/ToolCodeExecution"
             },
             {
               "type": "null"
             }
           ],
           "default": null,
-          "description": "Optional. Tool to support the model interacting directly with the computer. If enabled, it automatically populates computer-use specific Function Declarations."
+          "description": "Optional. CodeExecution tool type. Enables the model to execute code as part of generation."
         }
       },
       "title": "Tool",
@@ -4556,7 +4582,8 @@
       "type": "object"
     }
   },
-  "anyOf": [
+  "description": "The config for the YAML schema to create an agent.",
+  "oneOf": [
     {
       "$ref": "#/$defs/LlmAgentConfig"
     },
@@ -4573,6 +4600,5 @@
       "$ref": "#/$defs/BaseAgentConfig"
     }
   ],
-  "description": "The config for the YAML schema to create an agent.",
   "title": "AgentConfig"
 }
diff --git a/src/google/adk/agents/llm_agent_config.py b/src/google/adk/agents/llm_agent_config.py
@@ -37,7 +37,7 @@ class LlmAgentConfig(BaseAgentConfig):
       extra='forbid',
   )
 
-  agent_class: Literal['LlmAgent', ''] = Field(
+  agent_class: str = Field(
       default='LlmAgent',
       description=(
           'The value is used to uniquely identify the LlmAgent class. If it is'

diff --git a/src/google/adk/agents/loop_agent_config.py b/src/google/adk/agents/loop_agent_config.py
@@ -16,7 +16,6 @@
 
 from __future__ import annotations
 
-from typing import Literal
 from typing import Optional
 
 from pydantic import ConfigDict
@@ -34,7 +33,7 @@ class LoopAgentConfig(BaseAgentConfig):
       extra='forbid',
   )
 
-  agent_class: Literal['LoopAgent'] = Field(
+  agent_class: str = Field(
       default='LoopAgent',
       description='The value is used to uniquely identify the LoopAgent class.',
   )

diff --git a/src/google/adk/agents/parallel_agent_config.py b/src/google/adk/agents/parallel_agent_config.py
@@ -16,8 +16,6 @@
 
 from __future__ import annotations
 
-from typing import Literal
-
 from pydantic import ConfigDict
 from pydantic import Field
 
@@ -30,12 +28,12 @@ class ParallelAgentConfig(BaseAgentConfig):
   """The config for the YAML schema of a ParallelAgent."""
 
   model_config = ConfigDict(
-      extra='forbid',
+      extra="forbid",
   )
 
-  agent_class: Literal['ParallelAgent'] = Field(
-      default='ParallelAgent',
+  agent_class: str = Field(
+      default="ParallelAgent",
       description=(
-          'The value is used to uniquely identify the ParallelAgent class.'
+          "The value is used to uniquely identify the ParallelAgent class."
       ),
   )
diff --git a/src/google/adk/agents/sequential_agent_config.py b/src/google/adk/agents/sequential_agent_config.py
@@ -16,8 +16,6 @@
 
 from __future__ import annotations
 
-from typing import Literal
-
 from pydantic import ConfigDict
 from pydantic import Field
 
@@ -30,12 +28,12 @@ class SequentialAgentConfig(BaseAgentConfig):
   """The config for the YAML schema of a SequentialAgent."""
 
   model_config = ConfigDict(
-      extra='forbid',
+      extra="forbid",
   )
 
-  agent_class: Literal['SequentialAgent'] = Field(
-      default='SequentialAgent',
+  agent_class: str = Field(
+      default="SequentialAgent",
       description=(
-          'The value is used to uniquely identify the SequentialAgent class.'
+          "The value is used to uniquely identify the SequentialAgent class."
       ),
   )