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Hangfei LinandCopybara-Service
7415f2c094
**Highlights:** - **Callback Chaining:** Now supports a list of before and after callbacks, as in the non-live version. Callbacks are executed in order, stopping when one returns a response. - **Unit Tests:** Added new unit tests for before and after callbacks, async and sync versions, callback chains and mixed callbacks. - **Sample Agent:** Introduced a new example agent with multiple callbacks showing various behaviors: audit, security, validation, and enhancement. This provides practical usage examples. PiperOrigin-RevId: 783884562
94 lines
3.0 KiB
Markdown
94 lines
3.0 KiB
Markdown
# Live Tool Callbacks Agent
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This sample demonstrates how tool callbacks work in live (bidirectional streaming) mode. It showcases both `before_tool_callback` and `after_tool_callback` functionality with multiple callback chains, async callbacks, and various callback behaviors.
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## Features Demonstrated
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### Before Tool Callbacks
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1. **Audit Callback**: Logs all tool calls before execution
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2. **Security Callback**: Can block tool calls based on security rules (e.g., restricted locations)
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3. **Async Validation Callback**: Performs async validation and can prevent invalid operations
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### After Tool Callbacks
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1. **Enhancement Callback**: Adds metadata to tool responses
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2. **Async Post-processing Callback**: Performs async post-processing of responses
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### Tools Available
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- `get_weather`: Get weather information for any location
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- `calculate_async`: Perform mathematical calculations asynchronously
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- `log_activity`: Log activities with timestamps
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## Testing Scenarios
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### 1. Basic Callback Flow
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```
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"What's the weather in New York?"
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```
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Watch the console output to see:
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- Audit logging before the tool call
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- Security check (will pass for New York)
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- Response enhancement after the tool call
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### 2. Security Blocking
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```
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"What's the weather in classified?"
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```
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The security callback will block this request and return an error response.
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### 3. Validation Prevention
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```
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"Calculate 10 divided by 0"
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```
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The async validation callback will prevent division by zero.
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### 4. Multiple Tool Calls
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```
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"Get weather for London and calculate 5 + 3"
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```
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See how callbacks work with multiple parallel tool calls.
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### 5. Callback Chain Testing
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```
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"Log this activity: Testing callback chains"
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```
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Observe how multiple callbacks in the chain are processed.
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## Getting Started
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1. **Start the ADK Web Server**
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```bash
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adk web
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```
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2. **Access the ADK Web UI**
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Navigate to `http://localhost:8000`
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3. **Select the Agent**
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Choose "tool_callbacks_agent" from the dropdown in the top-left corner
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4. **Start Streaming**
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Click the **Audio** or **Video** icon to begin streaming
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5. **Test Callbacks**
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Try the testing scenarios above and watch both the chat responses and the console output to see callbacks in action
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## What to Observe
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- **Console Output**: Watch for callback logs with emojis:
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- 🔍 AUDIT: Audit callback logging
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- 🚫 SECURITY: Security callback blocking
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- ⚡ ASYNC BEFORE: Async preprocessing
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- ✨ ENHANCE: Response enhancement
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- 🔄 ASYNC AFTER: Async post-processing
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- **Enhanced Responses**: Tool responses will include additional metadata added by after callbacks
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- **Error Handling**: Security blocks and validation errors will be returned as proper error responses
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## Technical Notes
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- This sample demonstrates that tool callbacks now work identically in both regular and live streaming modes
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- Multiple callbacks are supported and processed in order
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- Both sync and async callbacks are supported
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- Callbacks can modify, enhance, or block tool execution
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- The callback system provides full control over the tool execution pipeline |