Agent Communication

Agent Communication

Expert guidance for designing robust multi-agent communication systems.

Core Message Types

AgentMessage (Request)

from pydantic import BaseModel, Field
from uuid import uuid4
from datetime import datetime

class AgentMessage(BaseModel):
    """Immutable message sent to an agent."""

    id: str = Field(default_factory=lambda: str(uuid4()))
    action: str  # e.g., "task_add", "storage_get"
    payload: dict[str, Any] = Field(default_factory=dict)
    correlation_id: str | None = None
    timestamp: datetime = Field(default_factory=datetime.utcnow)
    source_agent: str | None = None

    model_config = {"frozen": True}

AgentResponse (Reply)

class AgentResponse(BaseModel):
    """Response from an agent."""

    success: bool
    data: dict[str, Any] | None = None
    error_code: str | None = None
    error_message: str | None = None
    correlation_id: str | None = None
    source_agent: str | None = None

    @classmethod
    def ok(cls, data: dict[str, Any], **kwargs) -> "AgentResponse":
        return cls(success=True, data=data, **kwargs)

    @classmethod
    def error(cls, code: str, message: str, **kwargs) -> "AgentResponse":
        return cls(success=False, error_code=code, error_message=message, **kwargs)

Quick Routing Pattern

class OrchestratorAgent:
    """Routes messages to appropriate agents."""

    def __init__(self, agents: dict[str, BaseAgent]) -> None:
        self._agents = agents
        self._routes = {
            "task_": "task_manager",
            "storage_": "storage",
            "ui_": "ui_controller",
        }

    def handle_message(self, message: AgentMessage) -> AgentResponse:
        agent_name = self._resolve_route(message.action)
        if not agent_name:
            return AgentResponse.error("ROUTING_ERROR", f"Unknown action: {message.action}")

        agent = self._agents.get(agent_name)
        return agent.handle_message(message)

    def _resolve_route(self, action: str) -> str | None:
        for prefix, agent_name in self._routes.items():
            if action.startswith(prefix):
                return agent_name
        return None

Request-Response Flow

┌──────────┐    AgentMessage     ┌─────────────┐    AgentMessage     ┌─────────┐
│  Client  │───────────────────▶│ Orchestrator │───────────────────▶│  Agent  │
│          │                     │              │                     │         │
│          │◀───────────────────│              │◀───────────────────│         │
└──────────┘   AgentResponse     └─────────────┘   AgentResponse     └─────────┘

1. Client creates AgentMessage with action and payload
2. Orchestrator routes based on action prefix
3. Target agent processes and returns AgentResponse
4. Response propagates back through orchestrator

Reference Guides

For detailed patterns, see:

• Message Protocol: See references/message-protocol.md for complete message design, validation, and serialization
• Routing Patterns: See references/routing-patterns.md for prefix routing, registry patterns, and dynamic routing
• Error Handling: See references/error-handling.md for error propagation, error codes, and recovery patterns
• Async Messaging: See references/async-messaging.md for queue-based communication and async patterns
• Tracing Patterns: See references/tracing-patterns.md for correlation IDs, distributed tracing, and observability