Update ADK doc according to issue #866 - 3 - McpInstructionProvider to Fetch Instructions

docs/tools/mcp-tools.md

@@ -570,7 +570,7 @@ async def call_mcp_tool(
         return [mcp_types.TextContent(type="text", text=error_text)]
 
 # --- MCP Server Runner ---
-async def run_mcp_stdio_server():
+asynchronous def run_mcp_stdio_server():
     """Runs the MCP server, listening for connections over standard input/output."""
     # Use the stdio_server context manager from the mcp.server.stdio library
     async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
@@ -785,7 +785,6 @@ if __name__ == '__main__':
     asyncio.run(async_main())
   except Exception as e:
     print(f"An error occurred: {e}")
-```
 
 
 ## Key considerations
@@ -806,6 +805,52 @@ When working with MCP and ADK, keep these points in mind:
     * **Deployment:** This statefulness can pose challenges for scaling and deployment, especially for remote servers handling many users. The original MCP design often assumed client and server were co-located. Managing these persistent connections requires careful infrastructure considerations (e.g., load balancing, session affinity).
     * **ADK MCPToolset:** Manages this connection lifecycle. The exit\_stack pattern shown in the examples is crucial for ensuring the connection (and potentially the server process) is properly terminated when the ADK agent finishes.
 
+## Using `McpInstructionProvider` to Fetch Instructions
+
+In addition to fetching tools, you can also use MCP to dynamically provide instructions to your agents. The `McpInstructionProvider` allows you to fetch a prompt from an MCP server and use it as the instruction for your `LlmAgent`.
+
+This is particularly useful when you want to manage your agent's instructions centrally or update them without redeploying your agent.
+
+### How it Works
+
+1.  **Initialization:** You create an instance of `McpInstructionProvider`, passing it the connection parameters for your MCP server and the name of the prompt you want to fetch.
+2.  **Instruction Fetching:** When the agent runs, the `McpInstructionProvider` connects to the MCP server, fetches the specified prompt, and returns its content as the agent's instruction.
+3.  **Dynamic Arguments:** If the MCP prompt requires arguments, the `McpInstructionProvider` will look for them in the agent's context (`context.state`) and pass them to the MCP server when fetching the prompt.
+
+### Example Usage
+
+Here's how you can use `McpInstructionProvider` in your agent definition:
+
+```python
+from google.adk.agents import LlmAgent
+from google.adk.agents.mcp_instruction_provider import McpInstructionProvider
+from google.adk.tools.mcp_tool.mcp_session_manager import StdioConnectionParams
+from mcp import StdioServerParameters
+
+# Define the connection to your MCP server
+mcp_connection_params = StdioConnectionParams(
+    server_params=StdioServerParameters(
+        command='npx',
+        args=['-y', '@modelcontextprotocol/server-filesystem', '/path/to/your/folder'],
+    ),
+)
+
+# Create an agent with instructions fetched from the MCP server
+root_agent = LlmAgent(
+    model='gemini-2.0-flash',
+    name='dynamic_instruction_agent',
+    instruction=McpInstructionProvider(
+        connection_params=mcp_connection_params,
+        prompt_name='my_dynamic_prompt', # The name of the prompt to fetch
+    ),
+    tools=[
+        # ... your tools
+    ],
+)
+```
+
+In this example, the agent's instruction will be the content of the `my_dynamic_prompt` prompt fetched from the MCP server. If `my_dynamic_prompt` requires an argument, say `user_name`, you would need to ensure that `user_name` exists in the agent's state for the instruction to be fetched correctly.
+
 ## Deploying Agents with MCP Tools
 
 When deploying ADK agents that use MCP tools to production environments like Cloud Run, GKE, or Vertex AI Agent Engine, you need to consider how MCP connections will work in containerized and distributed environments.
@@ -1194,4 +1239,4 @@ MCPToolset(
 
 * [Model Context Protocol Documentation](https://modelcontextprotocol.io/ )
 * [MCP Specification](https://modelcontextprotocol.io/specification/)
-* [MCP Python SDK & Examples](https://github.com/modelcontextprotocol/)
+* [MCP Python SDK & Examples](https://github.com/modelcontextprotocol/)