04. MCP Protocol Deep Dive

class MockMCPServer:
    """A minimal MCP server implementation"""
 
    def __init__(self, name: str):
        self.name = name
        self.tools = {}
 
    def register_tool(self, name: str, description: str, handler: Callable):
        self.tools[name] = {
            "description": description,
            "handler": handler
        }
 
    def list_tools(self) -> List[Dict]:
        """Discovery endpoint - what can this server do?"""
        return [
            {"name": name, "description": tool["description"]}
            for name, tool in self.tools.items()
        ]
 
    def call_tool(self, name: str, arguments: Dict) -> Any:
        """Execute a tool by name"""
        if name not in self.tools:
            raise ValueError(f"Unknown tool: {name}")
        return self.tools[name]["handler"](**arguments)

class MCPClient:
    """Client that connects to MCP servers"""
 
    def __init__(self, servers: List[MockMCPServer]):
        self.servers = servers
 
    def discover_all_tools(self) -> List[Dict]:
        """Discover tools from all connected servers"""
        all_tools = []
        for server in self.servers:
            tools = server.list_tools()
            for tool in tools:
                tool["server"] = server.name
            all_tools.extend(tools)
        return all_tools
 
    def execute(self, server_name: str, tool_name: str, args: Dict):
        """Execute a tool on a specific server"""
        server = next(s for s in self.servers if s.name == server_name)
        return server.call_tool(tool_name, args)