feat(bq-plugin): Add A2A tool_origin detection for RemoteA2aAgent

Extends _get_tool_origin() to detect AgentTool wrapping a
RemoteA2aAgent and return "A2A" origin. Fixes existing test that
used private _agent attribute instead of public agent attribute,
and adds test for the new A2A origin path.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: caohy1988

src/google/adk/plugins/bigquery_agent_analytics_plugin.py

@@ -158,7 +158,7 @@ def _get_tool_origin(tool: "BaseTool") -> str:
       tool: The tool instance.
 
   Returns:
-      One of LOCAL, MCP, SUB_AGENT, TRANSFER_AGENT, or UNKNOWN.
+      One of LOCAL, MCP, A2A, SUB_AGENT, TRANSFER_AGENT, or UNKNOWN.
   """
   # Import lazily to avoid circular dependencies.
   # pylint: disable=g-import-not-at-top
@@ -171,12 +171,19 @@ def _get_tool_origin(tool: "BaseTool") -> str:
   except ImportError:
     McpTool = None
 
+  try:
+    from ..agents.remote_a2a_agent import RemoteA2aAgent  # pytype: disable=import-error
+  except ImportError:
+    RemoteA2aAgent = None
+
   # Order matters: TransferToAgentTool is a subclass of FunctionTool.
   if McpTool is not None and isinstance(tool, McpTool):
     return "MCP"
   if isinstance(tool, TransferToAgentTool):
     return "TRANSFER_AGENT"
   if isinstance(tool, AgentTool):
+    if RemoteA2aAgent is not None and isinstance(tool.agent, RemoteA2aAgent):
+      return "A2A"
     return "SUB_AGENT"
   if isinstance(tool, FunctionTool):
     return "LOCAL"

tests/unittests/plugins/test_bigquery_agent_analytics_plugin.py

@@ -4064,7 +4064,7 @@ def test_agent_tool_returns_sub_agent(self):
     agent = mock.MagicMock()
     agent.name = "sub"
     tool = AgentTool.__new__(AgentTool)
-    tool._agent = agent
+    tool.agent = agent
     tool._name = "sub"
     result = bigquery_agent_analytics_plugin._get_tool_origin(tool)
     assert result == "SUB_AGENT"
@@ -4085,6 +4085,23 @@ def test_mcp_tool_returns_mcp(self):
     result = bigquery_agent_analytics_plugin._get_tool_origin(tool)
     assert result == "MCP"
 
+  def test_a2a_agent_tool_returns_a2a(self):
+    from google.adk.tools.agent_tool import AgentTool
+
+    try:
+      from google.adk.agents.remote_a2a_agent import RemoteA2aAgent
+    except ImportError:
+      pytest.skip("A2A agent not available")
+
+    remote_agent = mock.MagicMock(spec=RemoteA2aAgent)
+    remote_agent.name = "remote"
+    remote_agent.description = "remote a2a agent"
+    tool = AgentTool.__new__(AgentTool)
+    tool.agent = remote_agent
+    tool._name = "remote"
+    result = bigquery_agent_analytics_plugin._get_tool_origin(tool)
+    assert result == "A2A"
+
   def test_unknown_tool_returns_unknown(self):
     tool = mock.MagicMock(spec=base_tool_lib.BaseTool)
     tool.name = "mystery"