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/.release-please-manifest.json

@@ -1,3 +0,0 @@
-{
-  ".": "1.24.1"
-}

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,69 +7,34 @@ assignees: ''
 
 ---
 
-## 🔴 Required Information
-*Please ensure all items in this section are completed to allow for efficient
-triaging. Requests without complete information may be rejected / deprioritized.
-If an item is not applicable to you - please mark it as N/A*
+** Please make sure you read the contribution guide and file the issues in the right place. **
+[Contribution guide.](https://google.github.io/adk-docs/contributing-guide/)
 
-**Describe the Bug:**
+**Describe the bug**
 A clear and concise description of what the bug is.
 
-**Steps to Reproduce:**
-Please provide a numbered list of steps to reproduce the behavior:
+**To Reproduce**
+Please share a minimal code and data to reproduce your problem.
+Steps to reproduce the behavior:
 1. Install '...'
 2. Run '....'
 3. Open '....'
-4. Provide error or stacktrace
+4. Provie error or stacktrace
 
-**Expected Behavior:**
+**Expected behavior**
 A clear and concise description of what you expected to happen.
 
-**Observed Behavior:**
-What actually happened? Include error messages or crash stack traces here.
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
 
-**Environment Details:**
-
- - ADK Library Version (pip show google-adk):
- - Desktop OS:** [e.g., macOS, Linux, Windows]
- - Python Version (python -V):
-
-**Model Information:**
+**Desktop (please complete the following information):**
+ - OS: [e.g. macOS, Linux, Windows]
+ - Python version(python -V):
+ - ADK version(pip show google-adk):
 
+ **Model Information:**
  - Are you using LiteLLM: Yes/No
- - Which model is being used: (e.g., gemini-2.5-pro)
+ - Which model is being used(e.g. gemini-2.5-pro)
 
----
-
-## 🟡 Optional Information
-*Providing this information greatly speeds up the resolution process.*
-
-**Regression:**
-Did this work in a previous version of ADK? If so, which one?
-
-**Logs:**
-Please attach relevant logs. Wrap them in code blocks (```) or attach a
-text file.
-```text
-// Paste logs here
-```
-
-**Screenshots / Video:**
-If applicable, add screenshots or screen recordings to help explain
-your problem.
-
-**Additional Context:**
+**Additional context**
 Add any other context about the problem here.
-
-**Minimal Reproduction Code:**
-Please provide a code snippet or a link to a Gist/repo that isolates the issue.
-```python
-// Code snippet here
-```
-
-**How often has this issue occurred?:**
-
- - Always (100%)
- - Often (50%+)
- - Intermittently (<50%)
- - Once / Rare

.github/ISSUE_TEMPLATE/feature_request.md

@@ -10,39 +10,14 @@ assignees: ''
 ** Please make sure you read the contribution guide and file the issues in the right place. **
 [Contribution guide.](https://google.github.io/adk-docs/contributing-guide/)
 
-## 🔴 Required Information
-*Please ensure all items in this section are completed to allow for efficient
-triaging. Requests without complete information may be rejected / deprioritized.
-If an item is not applicable to you - please mark it as N/A*
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
 
-### Is your feature request related to a specific problem?
-Please describe the problem you are trying to solve. (Ex: "I'm always frustrated
-when I have to manually handle X...")
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
 
-### Describe the Solution You'd Like
-A clear and concise description of the feature or API change you want.
-Be specific about input/outputs if this involves an API change.
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
 
-### Impact on your work
-How does this feature impact your work and what are you trying to achieve?
-If this is critical for you, tell us if there is a timeline by when you need
-this feature.
-
-### Willingness to contribute
-Are you interested in implementing this feature yourself or submitting a PR?
-(Yes/No)
-
----
-
-## 🟡 Recommended Information
-
-### Describe Alternatives You've Considered
-A clear and concise description of any alternative solutions or workarounds
-you've considered and why they didn't work for you.
-
-### Proposed API / Implementation
-If you have ideas on how this should look in code, please share a
-pseudo-code example.
-
-### Additional Context
-Add any other context or screenshots about the feature request here.
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/release-please-config.json

@@ -1,24 +0,0 @@
-{
-  "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json",
-  "packages": {
-    ".": {
-      "release-type": "python",
-      "package-name": "google-adk",
-      "include-component-in-tag": false,
-      "skip-github-release": true,
-      "changelog-path": "CHANGELOG.md",
-      "changelog-sections": [
-        {"type": "feat", "section": "Features"},
-        {"type": "fix", "section": "Bug Fixes"},
-        {"type": "perf", "section": "Performance Improvements"},
-        {"type": "refactor", "section": "Code Refactoring"},
-        {"type": "docs", "section": "Documentation"},
-        {"type": "test", "section": "Tests", "hidden": true},
-        {"type": "build", "section": "Build System", "hidden": true},
-        {"type": "ci", "section": "CI/CD", "hidden": true},
-        {"type": "style", "section": "Styles", "hidden": true},
-        {"type": "chore", "section": "Miscellaneous Chores", "hidden": true}
-      ]
-    }
-  }
-}

.github/release-please.yml

@@ -0,0 +1,5 @@
+releaseType: python
+handleGHRelease: true
+bumpMinorPreMajor: false
+extraFiles:
+  - src/google/adk/version.py

.github/release-trigger.yml

@@ -0,0 +1 @@
+enabled: true

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

@@ -16,15 +16,15 @@ 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: Load adk-bot SSH Private Key
-        uses: webfactory/ssh-agent@v0.9.1
+        uses: webfactory/ssh-agent@v0.9.0
         with:
           ssh-private-key: ${{ secrets.ADK_BOT_SSH_PRIVATE_KEY }}
 

.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.
@@ -26,14 +26,14 @@ 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: '3.11'
+          python-version: '3.x'
 
       - name: Install isort
         run: |

.github/workflows/mypy-new-errors.yml

@@ -1,74 +0,0 @@
-name: Mypy New Error Check
-
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-
-
-jobs:
-  mypy-diff:
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: ['3.10', '3.11', '3.12', '3.13',]
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v6
-        with:
-          fetch-depth: 0
-
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: ${{ matrix.python-version }}
-
-      - name: Install uv
-        uses: astral-sh/setup-uv@v7
-
-      - name: Generate Baseline (Main)
-        run: |
-          # Switch to main branch to generate baseline
-          git checkout origin/main
-
-          git checkout ${{ github.sha }} -- pyproject.toml
-          
-          # Install dependencies for main
-          uv venv .venv
-          source .venv/bin/activate
-          uv sync --all-extras
-          
-          # Run mypy, filter for errors only, remove line numbers (file:123: -> file::), and sort
-          # We ignore exit code (|| true) because we expect errors on main
-          uv run mypy . | grep "error:" | sed 's/:\([0-9]\+\):/::/g' | sort > main_errors.txt || true
-          
-          echo "Found $(wc -l < main_errors.txt) errors on main."
-
-      - name: Check PR Branch
-        run: |
-          # Switch back to the PR commit
-          git checkout ${{ github.sha }}
-          
-          # Re-sync dependencies in case the PR changed them
-          source .venv/bin/activate
-          uv sync --all-extras
-          
-          # Run mypy on PR code, apply same processing
-          uv run mypy . | grep "error:" | sed 's/:\([0-9]\+\):/::/g' | sort > pr_errors.txt || true
-          
-          echo "Found $(wc -l < pr_errors.txt) errors on PR branch."
-
-      - name: Compare and Fail on New Errors
-        run: |
-          # 'comm -13' suppresses unique lines in file1 (main) and common lines, 
-          # leaving only lines unique to file2 (PR) -> The new errors.
-          comm -13 main_errors.txt pr_errors.txt > new_errors.txt
-          
-          if [ -s new_errors.txt ]; then
-            echo "::error::The following NEW mypy errors were introduced:"
-            cat new_errors.txt
-            exit 1
-          else
-            echo "Great job! No new mypy errors introduced."
-          fi

.github/workflows/mypy.yml

@@ -1,32 +0,0 @@
-name: Mypy Type Check
-
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-
-jobs:
-  mypy:
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: ['3.10', '3.11', '3.12', '3.13',]
-
-    steps:
-      - uses: actions/checkout@v6
-
-      - name: Install uv
-        uses: astral-sh/setup-uv@v7
-
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: ${{ matrix.python-version }}
-
-      - name: Install dependencies
-        run: uv sync --all-extras
-
-      - name: Run mypy
-
-        run: uv run mypy . --strict

.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.
@@ -26,14 +26,14 @@ 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: '3.11'
+          python-version: '3.x'
 
       - name: Install pyink
         run: |

.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.
@@ -25,19 +25,19 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+        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 }}
 
     - name: Install the latest version of uv
-      uses: astral-sh/setup-uv@v7
+      uses: astral-sh/setup-uv@v6
 
     - name: Install dependencies
       run: |
@@ -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/release-cherry-pick.yml

@@ -1,46 +0,0 @@
-# Cherry-picks a commit from main to the release/candidate branch.
-# Use this to include bug fixes in an in-progress release.
-name: "Release: Cherry-pick"
-
-on:
-  workflow_dispatch:
-    inputs:
-      commit_sha:
-        description: 'Commit SHA to cherry-pick'
-        required: true
-        type: string
-
-permissions:
-  contents: write
-  actions: write
-
-jobs:
-  cherry-pick:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: release/candidate
-          fetch-depth: 0
-
-      - name: Configure git
-        run: |
-          git config user.name "github-actions[bot]"
-          git config user.email "github-actions[bot]@users.noreply.github.com"
-
-      - name: Cherry-pick commit
-        run: |
-          echo "Cherry-picking ${{ inputs.commit_sha }} to release/candidate"
-          git cherry-pick ${{ inputs.commit_sha }}
-
-      - name: Push changes
-        run: |
-          git push origin release/candidate
-          echo "Successfully cherry-picked commit to release/candidate"
-
-      - name: Trigger Release Please
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          gh workflow run release-please.yml --repo ${{ github.repository }}
-          echo "Triggered Release Please workflow"

.github/workflows/release-cut.yml

@@ -1,46 +0,0 @@
-# Starts the release process by creating a release/candidate branch.
-# Triggers release-please to generate a changelog PR.
-name: "Release: Cut"
-
-on:
-  workflow_dispatch:
-    inputs:
-      commit_sha:
-        description: 'Commit SHA to cut from (leave empty for latest main)'
-        required: false
-        type: string
-
-permissions:
-  contents: write
-  actions: write
-
-jobs:
-  cut-release:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ inputs.commit_sha || 'main' }}
-
-      - name: Check for existing release/candidate branch
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          if git ls-remote --exit-code --heads origin release/candidate &>/dev/null; then
-            echo "Error: release/candidate branch already exists"
-            echo "Please finalize or delete the existing release candidate before starting a new one"
-            exit 1
-          fi
-
-      - name: Create and push release/candidate branch
-        run: |
-          git checkout -b release/candidate
-          git push origin release/candidate
-          echo "Created branch: release/candidate"
-
-      - name: Trigger Release Please
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          gh workflow run release-please.yml --repo ${{ github.repository }}
-          echo "Triggered Release Please workflow"

.github/workflows/release-finalize.yml

@@ -1,66 +0,0 @@
-# Triggers when release-please PR is merged to release/candidate.
-# Creates the final release/v{version} branch and deletes the candidate branch.
-name: "Release: Finalize"
-
-on:
-  pull_request:
-    types: [closed]
-    branches:
-      - release/candidate
-
-permissions:
-  contents: write
-  pull-requests: write
-
-jobs:
-  finalize:
-    if: github.event.pull_request.merged == true
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check for release-please PR
-        id: check
-        env:
-          LABELS: ${{ toJson(github.event.pull_request.labels.*.name) }}
-        run: |
-          if echo "$LABELS" | grep -q "autorelease: pending"; then
-            echo "is_release_pr=true" >> $GITHUB_OUTPUT
-          else
-            echo "Not a release-please PR, skipping"
-            echo "is_release_pr=false" >> $GITHUB_OUTPUT
-          fi
-
-      - uses: actions/checkout@v4
-        if: steps.check.outputs.is_release_pr == 'true'
-        with:
-          ref: release/candidate
-
-      - name: Extract version from manifest
-        if: steps.check.outputs.is_release_pr == 'true'
-        id: version
-        run: |
-          VERSION=$(jq -r '.["."]' .github/.release-please-manifest.json)
-          echo "version=$VERSION" >> $GITHUB_OUTPUT
-          echo "Extracted version: $VERSION"
-
-      - name: Create release branch
-        if: steps.check.outputs.is_release_pr == 'true'
-        run: |
-          git checkout -b "release/v${{ steps.version.outputs.version }}"
-          git push origin "release/v${{ steps.version.outputs.version }}"
-          echo "Created branch: release/v${{ steps.version.outputs.version }}"
-
-      - name: Delete release/candidate branch
-        if: steps.check.outputs.is_release_pr == 'true'
-        run: |
-          git push origin --delete release/candidate
-          echo "Deleted branch: release/candidate"
-
-      - name: Update PR label to tagged
-        if: steps.check.outputs.is_release_pr == 'true'
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          gh pr edit ${{ github.event.pull_request.number }} \
-            --remove-label "autorelease: pending" \
-            --add-label "autorelease: tagged"
-          echo "Updated PR label to autorelease: tagged"

.github/workflows/release-please.yml

@@ -1,30 +0,0 @@
-# Runs release-please to create/update a PR with version bump and changelog.
-# Triggered by pushes to release/candidate or manually.
-name: "Release: Please"
-
-on:
-  push:
-    branches:
-      - release/candidate
-  workflow_dispatch:
-
-permissions:
-  contents: write
-  pull-requests: write
-
-jobs:
-  release-please:
-    # Skip if this is a release-please PR merge (handled by Release: Finalize)
-    if: "!startsWith(github.event.head_commit.message, 'chore(release')"
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: release/candidate
-
-      - uses: googleapis/release-please-action@v4
-        with:
-          token: ${{ secrets.RELEASE_PAT }}
-          config-file: .github/release-please-config.json
-          manifest-file: .github/.release-please-manifest.json
-          target-branch: release/candidate