Fix Google ADK extension documentation and log messages (#160)

* Initial plan

* Fix documentation and log message for in-place agent modification

Co-authored-by: JesuTerraz <96103167+JesuTerraz@users.noreply.github.com>

* Remove redundant comment from documentation example

Co-authored-by: JesuTerraz <96103167+JesuTerraz@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: JesuTerraz <96103167+JesuTerraz@users.noreply.github.com>

Author: Copilot

libraries/microsoft-agents-a365-tooling-extensions-google/docs/design.md

@@ -17,8 +17,8 @@ from microsoft_agents_a365.tooling.extensions.google import McpToolRegistrationS
 
 service = McpToolRegistrationService()
 
-# Create agent with MCP tools
-agent = await service.add_tool_servers_to_agent(
+# Add MCP tools to existing agent (modified in place)
+await service.add_tool_servers_to_agent(
     agent=existing_agent,
     auth=auth_context,
     auth_handler_name="graph",
@@ -39,7 +39,7 @@ McpToolRegistrationService.add_tool_servers_to_agent()
        │
        ├── Exchange token for MCP scope
        ├── Create McpToolset for each server
-       └── Create new Agent with all tools
+       └── Modify agent in place to add all tools
        │
        ▼
 Google ADK Agent with MCP tools

libraries/microsoft-agents-a365-tooling-extensions-google/microsoft_agents_a365/tooling/extensions/google/services/mcp_tool_registration_service.py

@@ -121,7 +121,8 @@ async def add_tool_servers_to_agent(
         all_tools = list(agent.tools) + mcp_servers_info
 
         self._logger.info(
-            f"Successfully configured {len(all_tools)} total MCP tool servers for agent"
+            f"Successfully configured agent with {len(mcp_servers_info)} MCP tool servers "
+            f"(total tools: {len(all_tools)})"
         )
 
         agent.tools = all_tools