Autonomous agents are quickly getting a practical stack: build agents with Google’s Agent Development Kit (ADK), publish and discover them via Coinbase’s x402 Bazaar, and enable compliant money flows using Agent Payments Pro (AP2). Below is a concise map of what each part does and how they fit together.

TL;DR — Key points

  • Build: Google Agent Development Kit offers a quickstart to scaffold tools, memory, and execution for agents on Vertex AI.
  • Discover: Coinbase x402 Bazaar is an agent/app directory and distribution surface with developer docs and launch guide.
  • Transact: AP2 (Agent Payments Pro) provides primitives for programmatic payments, wallets, and compliance rails.
  • A2A: Emerging agent‑to‑agent patterns enable agents to call misc agents and exchange value or capabilities.

Components at a glance

Google Agent Development Kit (ADK)

Google’s ADK (Vertex AI) provides scaffolding and runtime support to build agents that call tools, keep state, and orchestrate tasks. The Quickstart shows how to:

  • Define tools/functions an agent can invoke
  • Configure memory and planning/execution
  • Run locally or deploy to Google Cloud endpoints

Coinbase x402 and the Bazaar

x402 focuses on agent discovery, distribution, and mini-apps. The Bazaar launch and the developer docs outline:

  • How to publish agents or mini‑apps to a marketplace-like directory
  • Discovery metadata and versioning
  • Distribution surfaces and user onboarding

Agent Payments Pro (AP2)

AP2 adds payment primitives for agents: account creation, pay‑ins/pay‑outs, balances, and compliance tooling. Combined with x402, it enables agents to charge for work or pay misc agents.

A2A (Agent‑to‑Agent)

A2A patterns allow agents to invoke capabilities (e.g., retrieval, booking, payments). With AP2+x402, A2A can include metered usage and settlement.

How they fit together

  1. Develop your agent with ADK: tools, memory, execution loop.
  2. Distribute via x402 Bazaar: publish, document, and version your agent.
  3. Monetize with AP2: accept payments, pay collaborators or upstream agents.

Reference workflow (developer)

  • Locally using the ADK Quickstart.
  • Add core tools (search, RAG, service APIs) and guardrails.
  • Integrate AP2 for pricing and settlement (per task or subscription).
  • Publish to x402 Bazaar with clear metadata, pricing, and docs.
  • Enable A2A by exposing a simple, stable tool interface.

Risks and open questions

  • Compliance and KYC/AML responsibilities when agents move money
  • Trust, safety, and rate‑limiting for A2A invocation chains
  • Vendor lock‑in across cloud runtime vs. distribution/payment rails

Sources