fix(tools): Add proper cleanup for AgentTool to prevent MCP session errors

Clean up runner resources in AgentTool after sub-agent execution to ensure
MCP sessions are closed in the correct async task context. Without this fix,
MCP sessions were cleaned up during garbage collection in a different task,
causing "Attempted to exit cancel scope in a different task" errors.

This fix ensures that `runner.close()` is called immediately after the
sub-agent finishes executing, properly closing all MCP sessions and other
resources within the same async task context they were created in.

Also adds two demo agents showing how to use AgentTool with MCP tools:
- mcp_in_agent_tool_remote: Uses SSE mode (remote server connection)
- mcp_in_agent_tool_stdio: Uses stdio mode (local subprocess)

Both demos use Gemini 2.5 Flash and include zero-installation setup using uvx.

Related: #1112, #929

.github/ISSUE_TEMPLATE/bug_report.md

@@ -19,7 +19,7 @@ Steps to reproduce the behavior:
 1. Install '...'
 2. Run '....'
 3. Open '....'
-4. Provide error or stacktrace
+4. Provie error or stacktrace
 
 **Expected behavior**
 A clear and concise description of what you expected to happen.

.github/workflows/analyze-releases-for-adk-docs-updates.yml

@@ -16,10 +16,10 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
         with:
           python-version: '3.11'
 

.github/workflows/check-file-contents.yml

@@ -1,4 +1,4 @@
-# Copyright 2026 Google LLC
+# Copyright 2025 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
         with:
           fetch-depth: 2
 
@@ -96,7 +96,7 @@ jobs:
             echo ""
 
             set +e
-            FILES_WITH_FORBIDDEN_IMPORT=$(grep -lE '^from.*\bcli\b.*import.*$' $CHANGED_FILES)
+            FILES_WITH_FORBIDDEN_IMPORT=$(grep -lE '^from.*cli.*import.*$' $CHANGED_FILES)
             GREP_EXIT_CODE=$?
             set -e
 

.github/workflows/copybara-pr-handler.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
       - name: Check for Copybara commits and close PRs
-        uses: actions/github-script@v8
+        uses: actions/github-script@v7
         with:
           github-token: ${{ secrets.ADK_TRIAGE_AGENT }}
           script: |

.github/workflows/discussion_answering.yml

@@ -15,16 +15,16 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
         with:
           python-version: '3.11'
 
       - name: Authenticate to Google Cloud
         id: auth
-        uses: 'google-github-actions/auth@v3'
+        uses: 'google-github-actions/auth@v2'
         with:
           credentials_json: '${{ secrets.ADK_GCP_SA_KEY }}'
 

.github/workflows/isort.yml

@@ -1,4 +1,4 @@
-# Copyright 2026 Google LLC
+# Copyright 2025 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -26,12 +26,12 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
         with:
           fetch-depth: 2
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
         with:
           python-version: '3.x'
 

.github/workflows/pr-triage.yml

@@ -20,10 +20,10 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
         with:
           python-version: '3.11'
 

.github/workflows/pyink.yml

@@ -1,4 +1,4 @@
-# Copyright 2026 Google LLC
+# Copyright 2025 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -26,12 +26,12 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
         with:
           fetch-depth: 2
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
         with:
           python-version: '3.x'
 

.github/workflows/python-unit-tests.yml

@@ -1,4 +1,4 @@
-# Copyright 2026 Google LLC
+# Copyright 2025 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -25,14 +25,14 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v6
+      uses: actions/checkout@v4
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v6
+      uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python-version }}
 
@@ -48,6 +48,14 @@ jobs:
     - name: Run unit tests with pytest
       run: |
         source .venv/bin/activate
-        pytest tests/unittests \
-          --ignore=tests/unittests/artifacts/test_artifact_service.py \
-          --ignore=tests/unittests/tools/google_api_tool/test_googleapi_to_openapi_converter.py
+        if [[ "${{ matrix.python-version }}" == "3.9" ]]; then
+          pytest tests/unittests \
+            --ignore=tests/unittests/a2a \
+            --ignore=tests/unittests/tools/mcp_tool \
+            --ignore=tests/unittests/artifacts/test_artifact_service.py \
+            --ignore=tests/unittests/tools/google_api_tool/test_googleapi_to_openapi_converter.py
+        else
+          pytest tests/unittests \
+            --ignore=tests/unittests/artifacts/test_artifact_service.py \
+            --ignore=tests/unittests/tools/google_api_tool/test_googleapi_to_openapi_converter.py
+        fi

.github/workflows/stale-bot.yml

@@ -1,58 +0,0 @@
-# Copyright 2026 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-name: ADK Stale Issue Auditor
-
-on:
-  workflow_dispatch:
-
-  schedule:
-    # This runs at 6:00 AM UTC (10 PM PST)
-    - cron: '0 6 * * *'
-
-jobs:
-  audit-stale-issues:
-    if: github.repository == 'google/adk-python'
-    runs-on: ubuntu-latest
-    timeout-minutes: 60
-
-    permissions:
-      issues: write
-      contents: read
-
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@v6
-
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: '3.11'
-
-      - name: Install dependencies
-        run: |
-          python -m pip install --upgrade pip
-          pip install requests google-adk
-
-      - name: Run Auditor Agent Script
-        env:
-          GITHUB_TOKEN: ${{ secrets.ADK_TRIAGE_AGENT }}
-          GOOGLE_API_KEY: ${{ secrets.GOOGLE_API_KEY }}
-          OWNER: ${{ github.repository_owner }}
-          REPO: adk-python
-          CONCURRENCY_LIMIT: 3
-          LLM_MODEL_NAME: "gemini-2.5-flash"
-          PYTHONPATH: contributing/samples
-
-        run: python -m adk_stale_agent.main

.github/workflows/triage.yml

@@ -2,34 +2,21 @@ name: ADK Issue Triaging Agent
 
 on:
   issues:
-    types: [opened, labeled]
-  schedule:
-    # Run every 6 hours to triage untriaged issues
-    - cron: '0 */6 * * *'
+    types: [opened, reopened]
 
 jobs:
   agent-triage-issues:
     runs-on: ubuntu-latest
-    # Run for:
-    # - Scheduled runs (batch processing)
-    # - New issues (need component labeling)
-    # - Issues labeled with "planned" (need owner assignment)
-    if: >-
-      github.repository == 'google/adk-python' && (
-        github.event_name == 'schedule' ||
-        github.event.action == 'opened' ||
-        github.event.label.name == 'planned'
-      )
     permissions:
       issues: write
       contents: read
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
         with:
           python-version: '3.11'
 
@@ -43,8 +30,8 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.ADK_TRIAGE_AGENT }}
           GOOGLE_API_KEY: ${{ secrets.GOOGLE_API_KEY }}
           GOOGLE_GENAI_USE_VERTEXAI: 0
-          OWNER: ${{ github.repository_owner }}
-          REPO: ${{ github.event.repository.name }}
+          OWNER: 'google'
+          REPO: 'adk-python'
           INTERACTIVE: 0
           EVENT_NAME: ${{ github.event_name }} # 'issues', 'schedule', etc.
           ISSUE_NUMBER: ${{ github.event.issue.number }}

.github/workflows/upload-adk-docs-to-vertex-ai-search.yml

@@ -9,12 +9,11 @@ on:
 
 jobs:
   upload-adk-docs-to-vertex-ai-search:
-    if: github.repository == 'google/adk-python'
     runs-on: ubuntu-latest
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
 
       - name: Clone adk-docs repository
         run: git clone https://github.com/google/adk-docs.git /tmp/adk-docs
@@ -23,13 +22,13 @@ jobs:
         run: git clone https://github.com/google/adk-python.git /tmp/adk-python
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
         with:
           python-version: '3.11'
 
       - name: Authenticate to Google Cloud
         id: auth
-        uses: 'google-github-actions/auth@v3'
+        uses: 'google-github-actions/auth@v2'
         with:
           credentials_json: '${{ secrets.ADK_GCP_SA_KEY }}'
 

.gitignore

@@ -101,7 +101,6 @@ Thumbs.db
 
 # AI Coding Tools - Project-specific configs
 # Developers should symlink or copy AGENTS.md and add their own overrides locally
-.adk/
 .claude/
 CLAUDE.md
 .cursor/

CONTRIBUTING.md

@@ -56,14 +56,14 @@ information on using pull requests.
 
 ### Requirement for PRs
 
--   All PRs, other than small documentation or typo fixes, should have an Issue
+-   All PRs, other than small documentation or typo fixes, should have a Issue
     associated. If a relevant issue doesn't exist, please create one first or
     you may instead describe the bug or feature directly within the PR
     description, following the structure of our issue templates.
 -   Small, focused PRs. Keep changes minimal—one concern per PR.
 -   For bug fixes or features, please provide logs or screenshot after the fix
     is applied to help reviewers better understand the fix.
--   Please include a `testing plan` section in your PR to describe how you
+-   Please include a `testing plan` section in your PR to talk about how you
     will test. This will save time for PR review. See `Testing Requirements`
     section for more details.
 
@@ -126,7 +126,7 @@ Depending on your change:
 
 For any changes that impact user-facing documentation (guides, API reference,
 tutorials), please open a PR in the
-[adk-docs](https://github.com/google/adk-docs) repository to update the relevant
+[adk-docs](https://github.com/google/adk-docs) repository to update relevant
 part before or alongside your code PR.
 
 ## Development Setup
@@ -145,7 +145,7 @@ part before or alongside your code PR.
 
 3.  **Create and activate a virtual environment:**
 
-    **NOTE**: ADK supports Python 3.10+. Python 3.11 and above is strongly
+    **NOTE**: ADK supports Python 3.9+. Python 3.11 and above is strongly
     recommended.
 
     Create a workspace venv using uv.
@@ -160,11 +160,7 @@ part before or alongside your code PR.
     source .venv/bin/activate
     ```
 
-    **Windows**
-
-    ```shell
-    source .\.venv\Scripts\activate
-    ```
+    **windows** `shell source .\.venv\Scripts\activate`
 
 4.  **Install dependencies:**
 
@@ -234,7 +230,7 @@ part before or alongside your code PR.
 ## Contributing Resources
 
 [Contributing folder](https://github.com/google/adk-python/tree/main/contributing)
-has resources that are helpful for contributors.
+has resources that is helpful for contributors.
 
 ## Vibe Coding
 

README.md

@@ -4,7 +4,7 @@
 [![PyPI](https://img.shields.io/pypi/v/google-adk)](https://pypi.org/project/google-adk/)
 [![Python Unit Tests](https://github.com/google/adk-python/actions/workflows/python-unit-tests.yml/badge.svg)](https://github.com/google/adk-python/actions/workflows/python-unit-tests.yml)
 [![r/agentdevelopmentkit](https://img.shields.io/badge/Reddit-r%2Fagentdevelopmentkit-FF4500?style=flat&logo=reddit&logoColor=white)](https://www.reddit.com/r/agentdevelopmentkit/)
-<a href="https://codewiki.google/github.com/google/adk-python"><img src="https://www.gstatic.com/_/boq-sdlc-agents-ui/_/r/Mvosg4klCA4.svg" alt="Ask Code Wiki" height="20"></a>
+[![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/google/adk-python)
 
 <html>
     <h2 align="center">
@@ -17,8 +17,7 @@
       Important Links:
       <a href="https://google.github.io/adk-docs/">Docs</a>,
       <a href="https://github.com/google/adk-samples">Samples</a>,
-      <a href="https://github.com/google/adk-java">Java ADK</a>,
-      <a href="https://github.com/google/adk-go">Go ADK</a> &
+      <a href="https://github.com/google/adk-java">Java ADK</a> &
       <a href="https://github.com/google/adk-web">ADK Web</a>.
     </h3>
 </html>
@@ -33,7 +32,7 @@ deployment-agnostic, and compatible with other frameworks.
 
 ## 🔥 What's new
 
-- **Custom Service Registration**: Add a service registry to provide a generic way to register custom service implementations to be used in FastAPI server. See [short instruction](https://github.com/google/adk-python/discussions/3175#discussioncomment-14745120). ([391628f](https://github.com/google/adk-python/commit/391628fcdc7b950c6835f64ae3ccab197163c990))
+- **Custom Service Registration**: Add a service registry to provide a generic way to register custom service implementations to be used in FastAPI server. See short instruction [here](https://github.com/google/adk-python/discussions/3175#discussioncomment-14745120). ([391628f](https://github.com/google/adk-python/commit/391628fcdc7b950c6835f64ae3ccab197163c990))
 
 - **Rewind**: Add the ability to rewind a session to before a previous invocation ([9dce06f](https://github.com/google/adk-python/commit/9dce06f9b00259ec42241df4f6638955e783a9d1)).
 
@@ -158,13 +157,13 @@ We welcome contributions from the community! Whether it's bug reports, feature r
 
 ## Community Repo
 
-We have [adk-python-community repo](https://github.com/google/adk-python-community) that is home to a growing ecosystem of community-contributed tools, third-party
+We have [adk-python-community repo](https://github.com/google/adk-python-community)that is home to a growing ecosystem of community-contributed tools, third-party
 service integrations, and deployment scripts that extend the core capabilities
 of the ADK.
 
 ## Vibe Coding
 
-If you want to develop agent via vibe coding the [llms.txt](./llms.txt) and the [llms-full.txt](./llms-full.txt) can be used as context to LLM. While the former one is a summarized one and the later one has the full information in case your LLM has big enough context window.
+If you are to develop agent via vibe coding the [llms.txt](./llms.txt) and the [llms-full.txt](./llms-full.txt) can be used as context to LLM. While the former one is a summarized one and the later one has the full information in case your LLM has big enough context window.
 
 ## Community Events
 

autoformat.sh

@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2026 Google LLC
+# Copyright 2025 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

contributing/README.md

@@ -1,6 +1,6 @@
 # Contributing Resources
 
-This folder hosts resources for ADK contributors, for example, testing samples etc.
+This folder host resources for ADK contributors, for example, testing samples etc.
 
 ## Samples
 
@@ -13,4 +13,4 @@ Samples folder host samples to test different features. The samples are usually
 The [adk_project_overview_and_architecture.md](adk_project_overview_and_architecture.md) describes the ADK project overview and its technical architecture from high-level.
 
 This is helpful for contributors to understand the project and design philosophy.
- It can also be fed into LLMs for vibe-coding.
+ It can also be feed into LLMs for vibe-coding.

contributing/adk_project_overview_and_architecture.md

@@ -34,7 +34,7 @@ my_adk_project/
     └── my_app/
         ├── agents/
         │   ├── my_agent/
-        │   │   ├── __init__.py   # Must contain: from . import agent \
+        │   │   ├── __init__.py   # Must contain: from. import agent \
         │   │   └── agent.py      # Must contain: root_agent = Agent(...) \
         │   └── another_agent/
         │       ├── __init__.py
@@ -43,7 +43,7 @@ my_adk_project/
 
 agent.py: Must define the agent and assign it to a variable named root_agent. This is how ADK's tools find it.
 
-`__init__.py`: In each agent directory, it must contain `from . import agent` to make the agent discoverable.
+`__init__.py`: In each agent directory, it must contain from. import agent to make the agent discoverable.
 
 ## Local Development & Debugging
 
@@ -69,7 +69,7 @@ We expose agents as production APIs using FastAPI.
 
 - Custom Endpoints: We can add our own routes (e.g., /health) to the app object returned by the helper.
 
-```Python
+Python
 
 from google.adk.cli.fast_api import get_fast_api_app
 app = get_fast_api_app(agent_dir="./agents")
@@ -77,7 +77,6 @@ app = get_fast_api_app(agent_dir="./agents")
 @app.get("/health")
 async def health_check():
     return {"status": "ok"}
-```
 
 
 ## Deployment to Production