From d0f49487058e5da462f650467c7baa6f7ef14ea5 Mon Sep 17 00:00:00 2001
From: Fedor V <738925+sumkincpp@users.noreply.github.com>
Date: Wed, 26 Nov 2025 19:33:03 +0100
Subject: [PATCH 1/2] fix(agent_tool): handle case when last_content.parts are
 unavailable

---
 src/google/adk/tools/agent_tool.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/google/adk/tools/agent_tool.py b/src/google/adk/tools/agent_tool.py
index 46d8616619..f700cdd822 100644
--- a/src/google/adk/tools/agent_tool.py
+++ b/src/google/adk/tools/agent_tool.py
@@ -186,7 +186,7 @@ async def run_async(
     # to avoid "Attempted to exit cancel scope in a different task" errors
     await runner.close()
 
-    if not last_content:
+    if not last_content or not last_content.parts:
       return ''
     merged_text = '\n'.join(p.text for p in last_content.parts if p.text)
     if isinstance(self.agent, LlmAgent) and self.agent.output_schema:

From 87fca92bcafa42608d4e0087781c39a15db2b641 Mon Sep 17 00:00:00 2001
From: Fedor V <738925+sumkincpp@users.noreply.github.com>
Date: Wed, 26 Nov 2025 19:54:27 +0100
Subject: [PATCH 2/2] fix(agent_tool): case when merged_text is empty

---
 src/google/adk/tools/agent_tool.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/google/adk/tools/agent_tool.py b/src/google/adk/tools/agent_tool.py
index f700cdd822..e08b71d159 100644
--- a/src/google/adk/tools/agent_tool.py
+++ b/src/google/adk/tools/agent_tool.py
@@ -189,6 +189,9 @@ async def run_async(
     if not last_content or not last_content.parts:
       return ''
     merged_text = '\n'.join(p.text for p in last_content.parts if p.text)
+    # no text present -> no json, return empty string
+    if not merged_text:
+      return ''
     if isinstance(self.agent, LlmAgent) and self.agent.output_schema:
       tool_result = self.agent.output_schema.model_validate_json(
           merged_text