Category: Messaging Maturity: ★★ Established Also known as: Point-to-Point Channel, Task Delegation, Direct Call
Send a task from one agent to exactly one other agent through a dedicated point-to-point channel.
You have identified a specific agent that has the capability to handle a subtask. The calling agent knows the receiver's identity (via prior discovery or hard-coded routing) and expects a structured result back.
An agent needs to delegate a specific subtask to another agent with known capabilities. Broadcasting to all agents wastes resources, and the sender needs a reliable response — not just fire-and-forget.
- F1 Latency vs. F2 Coupling — direct calls have minimal latency (no intermediary) but create tight coupling: the sender must know the receiver's address. If the receiver moves or is replaced, the sender must change.
- F8 Determinism — the one-to-one channel makes the flow predictable and easy to trace: exactly one agent receives and handles the message.
Establish a dedicated channel between two agents. The sender pushes a structured message (task + context) to the receiver's endpoint. The receiver acknowledges receipt, processes the task, and returns a result. The channel is exclusive to this sender-receiver pair for the duration of the task.
Runnable implementation: samples/python/messaging/direct_message.py
# Agent A delegates a task directly to Agent B
result = agent_b.invoke({"question": agent_a.generate_question()})- ✅ Simple, predictable, and easy to trace in logs
- ✅ Result is returned synchronously or via callback; no polling needed
- ✅ Minimal latency — no intermediary hop (F1 resolved)
- ✅ Explicit, traceable message flow (F8, F6 resolved)
- ❌ Tight coupling — sender must know receiver address (F2 introduced)
- ❌ No load balancing or failover without additional infrastructure
- ❌ If the receiver is down, the sender must handle the failure explicitly
- When the receiver identity may change at runtime — use Agent Card Registry + Content-Based Router instead.
- When you need broadcast semantics — use Broadcast Message.
- When decoupling matters more than simplicity.
Per FAILURE-MAP.md:
- FM-1.4 Loss of context ◐ — context is passed explicitly in every message, reducing silent context loss.
- FM-2.4 Information withholding ◐ — the receiving agent gets the full task description in one structured message.
- Google A2A Protocol — the primary mechanism for agent-to-agent task delegation; each task is a Direct Message to a specific Agent Card endpoint
- LangGraph node edges — edges between nodes in a StateGraph are point-to-point: output of node A flows to node B and nowhere else
- ReAct agents (tool calls) — when an agent invokes a tool, the tool call is a direct message to that tool's handler
- used-by Supervised Delegation — the supervisor delegates via Direct Message.
- alternative-to Broadcast Message — when exactly one agent should handle the task.
- uses Agent Card Registry — to discover the receiver address before sending.
- Hohpe, G. & Woolf, B. (2003). Enterprise Integration Patterns — Point-to-Point Channel.
- Google (2025). Agent-to-Agent (A2A) Protocol Specification.