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Paper·arxiv.org
ai-agentsllmresearchevaluationarchitecture

Natural-Language Agent Harnesses

Improve natural-language agent reliability and performance by externalizing and standardizing their high-level control logic. This approach makes agent designs modular, testable, and easier to compare, accelerating robust AI development.

intermediate1 hour5 steps
The play
  1. Decouple Control Logic
    Separate the high-level decision-making and flow control of your agent from its core task execution components (e.g., LLM calls, tool use).
  2. Define a Harness Interface
    Establish clear, standardized input and output contracts (APIs) for your externalized control logic to interact with the agent's sensors and effectors.
  3. Create a Dedicated Harness Module
    Implement the decoupled control logic within a distinct module, class, or configuration file, making it independently deployable and testable.
  4. Enable Strategy Swapping
    Design the harness to easily allow switching between different control strategies or algorithms without modifying the agent's core functionalities.
  5. Develop Evaluation Frameworks
    Build or adapt tools to systematically test and compare the performance of various harness designs against defined metrics and benchmarks.
Starter code
class AgentControlHarness:
    def __init__(self, agent_config):
        self.config = agent_config
        # Load specific control strategy based on config
        self.strategy = self._load_strategy(agent_config.get("control_strategy", "default"))

    def _load_strategy(self, strategy_name):
        # Placeholder for loading actual strategy implementation
        if strategy_name == "default":
            return DefaultControlStrategy()
        elif strategy_name == "sequential":
            return SequentialControlStrategy()
        else:
            raise ValueError(f"Unknown strategy: {strategy_name}")

    def decide_next_action(self, observations, current_state):
        # Delegate decision making to the loaded strategy
        return self.strategy.determine_action(observations, current_state)

    def update_state(self, action, result):
        # Delegate state updates to the loaded strategy
        return self.strategy.update_internal_state(action, result)

class DefaultControlStrategy:
    def determine_action(self, observations, current_state):
        print("Default strategy: Deciding action...")
        return {"action_type": "query_llm", "prompt": "What should I do next?"}

    def update_internal_state(self, action, result):
        print("Default strategy: Updating state...")
        return {"status": "processed", "last_action": action, "last_result": result}

# Example Usage (conceptual):
if __name__ == "__main__":
    agent_configuration = {
        "control_strategy": "default",
        "llm_model": "gpt-4",
        "max_retries": 3
    }
    harness = AgentControlHarness(agent_configuration)

    observations = {"user_input": "Summarize this document.", "context": "..."}
    current_state = {"task_status": "new", "history": []}

    action = harness.decide_next_action(observations, current_state)
    print(f"Agent decided: {action}")
    new_state = harness.update_state(action, {"result": "LLM responded with summary."})
    print(f"Agent state updated: {new_state}")
Source
Natural-Language Agent Harnesses — Action Pack