Update ADK doc according to issue #744 - 8

docs/plugins/reflect-retry-tool-plugin.md

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+# Reflect and Retry Tool Plugin
+
+The `ReflectAndRetryToolPlugin` provides self-healing, concurrent-safe error recovery for tool failures. This plugin intercepts tool failures, provides structured guidance to the LLM for reflection and correction, and retries the operation up to a configurable limit.
+
+## Key Features
+
+- **Concurrency Safe:** Uses locking to safely handle parallel tool executions.
+- **Configurable Scope:** Tracks failures per-invocation (default) or globally using the `TrackingScope` enum.
+- **Extensible Scoping:** The `_get_scope_key` method can be overridden to implement custom tracking logic (e.g., per-user or per-session).
+- **Granular Tracking:** Failure counts are tracked per-tool within the defined scope. A success with one tool resets its counter without affecting others.
+- **Custom Error Extraction:** Supports detecting errors in normal tool responses that don't throw exceptions, by overriding the `extract_error_from_result` method.
+
+## How to Use
+
+To use the `ReflectAndRetryToolPlugin`, add it to the `plugins` list in your `App` configuration.
+
+### Basic Usage
+
+The most common usage is to track failures only within the current agent invocation.
+
+```python
+from google.adk.plugins import ReflectAndRetryToolPlugin
+
+# Track failures only within the current agent invocation (default).
+error_handling_plugin = ReflectAndRetryToolPlugin(max_retries=3)
+
+app = App(
+    # ...
+    plugins=[error_handling_plugin],
+)
+```
+
+### Global Scope
+
+You can track failures globally across all turns and users.
+
+```python
+from google.adk.plugins import ReflectAndRetryToolPlugin, TrackingScope
+
+# Track failures globally across all turns and users.
+global_error_handling_plugin = ReflectAndRetryToolPlugin(
+    max_retries=5,
+    scope=TrackingScope.GLOBAL
+)
+
+app = App(
+    # ...
+    plugins=[global_error_handling_plugin],
+)
+```
+
+### Disabling Exceptions
+
+You can configure the plugin to not throw an exception when the retry limit is exceeded and instead return guidance to the LLM.
+
+```python
+from google.adk.plugins import ReflectAndRetryToolPlugin
+
+# Retry on failures but do not throw exceptions.
+error_handling_plugin = ReflectAndRetryToolPlugin(
+    max_retries=3,
+    throw_exception_if_retry_exceeded=False
+)
+
+app = App(
+    # ...
+    plugins=[error_handling_plugin],
+)
+```
+
+### Custom Error Extraction
+
+You can create a custom plugin that inherits from `ReflectAndRetryToolPlugin` to detect errors in successful tool responses that contain error messages.
+
+```python
+from google.adk.plugins import ReflectAndRetryToolPlugin
+
+class CustomRetryPlugin(ReflectAndRetryToolPlugin):
+  async def extract_error_from_result(self, *, tool, tool_args, tool_context, result):
+    # Detect error based on response content
+    if result.get('status') == 'error':
+        return result
+    return None  # No error detected
+
+error_handling_plugin = CustomRetryPlugin(max_retries=5)
+
+app = App(
+    # ...
+    plugins=[error_handling_plugin],
+)
+```