from typing import Dict, List

class Agent:
    def __init__(self, name: str):
        self.name = name
        self.task_log = []

    def receive_task(self, task: str) -> str:
        self.task_log.append(task)
        return f"Agent {self.name} received task: {task}"

    def get_tasks(self) -> List[str]:
        return self.task_log

class MultiAgentCoordinator:
    def __init__(self):
        self.agents: Dict[str, Agent] = {}

    def register_agent(self, name: str) -> str:
        if name not in self.agents:
            self.agents[name] = Agent(name)
            return f"Agent '{name}' registered."
        return f"Agent '{name}' already exists."

    def assign_task(self, agent_name: str, task: str) -> str:
        if agent_name in self.agents:
            return self.agents[agent_name].receive_task(task)
        return f"Agent '{agent_name}' not found."

    def get_all_tasks(self) -> Dict[str, List[str]]:
        return {name: agent.get_tasks() for name, agent in self.agents.items()}