Update examples

Author: RussellLuo

examples/mcp/agent.py

@@ -1,6 +1,7 @@
 import asyncio
 
 from coagent.agents import MCPAgent
+from coagent.agents.mcp_agent import Prompt
 from coagent.core import AgentSpec, idle_loop, new, set_stderr_logger
 from coagent.runtimes import NATSRuntime
 
@@ -9,7 +10,7 @@
     "mcp",
     new(
         MCPAgent,
-        system="""You are an agent who can use tools.""",
+        system=Prompt(name="system_prompt", arguments={"role": "Weather Reporter"}),
         mcp_server_base_url="http://localhost:8080",
     ),
 )

examples/mcp/server.py

@@ -3,6 +3,12 @@
 mcp = FastMCP("Weather", port=8080)
 
 
+@mcp.prompt()
+def system_prompt(role: str) -> str:
+    """Create a system prompt."""
+    return f"You are a helpful {role}."
+
+
 @mcp.tool()
 def query_weather(city: str) -> str:
     """Query the weather in the given city."""