Phase 2: Coordination & Agreement · ~75 minutes · Python (stdlib · `http.server` · `json`)

A2A — The Agent-to-Agent Protocol

Google announced A2A in April 2025; by April 2026 the spec is at https://a2a-protocol.org/latest/specification/ and 150+ organizations back it.

Hiring signal: Can operate a2a in production

Introduction

A2A is the horizontal complement to MCP (Lesson 13): where MCP is vertical (agent ↔ tools), A2A is peer-to-peer (agent ↔ agent). It defines Agent Cards (discovery), tasks with artifacts (text, structured data, video), opaque task lifecycles, and auth. Production systems increasingly pair MCP with A2A. Google Cloud rolled A2A support into Vertex AI Agent Builder during 2025-2026.

Type: Learn + Build Languages: Python (stdlib, http.server, json) Prerequisites: Phase 16 · 04 (Primitive Model) Time: ~75 minutes

Objective

Learning objectives

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