A2A: agents delegating to agents
As of 2026-10-15, 14 listed tools say they support Agent2Agent; highest Sato Scores: Bankr, Agent Payments Protocol (AP2) and Lucid Agents.data: JSON · CSV
- Implementations14
- Sato Scored14
- Deploy specs9
- Updated2026-10-15
A2A covers the case MCP doesn't: not an agent calling a tool, but an agent handing work to another agent. Each participant publishes a card describing what it can do and how to reach it, and an orchestrator reads those cards to decide where to route a task.
It's the newest of the standards tracked here and the least settled. The listings below implement some part of it; read each one for which part, because coverage varies a great deal.
A2A: 14 listings, 10 open source and 4 with a commit or release in the last 30 days; top Sato Scores: Bankr (87), Agent Payments Protocol (AP2) (72), Lucid Agents (71), as of 2026-10-15.
API / SDK
3Agently
EarlyRouting and settlement layer and CLI for agent-to-agent commerce, supporting EVM wallets, agent discovery, A2A messaging, x402 payments, and ERC-8004 identity.
Universal Commerce Protocol (UCP)
ActiveOpen standard co-developed by Google and Shopify for AI agents to discover, negotiate, and transact with any merchant across the full commerce journey.
Agent0 SDK
UnknownTypeScript and Python SDKs to register an agent on ERC-8004, publish its MCP and A2A endpoints, and search for or give feedback on other agents.
Payment Rail
3Agent Payments Protocol (AP2)
ActiveOpen protocol from Google for secure agent-led payments across traditional and crypto rails, with a crypto-native x402 extension built with Coinbase, Ethereum Foundation, and MetaMask.
Nevermined
UnknownTypeScript SDK to put a payment plan in front of an agent: credit or time-based plans, x402 access tokens, and A2A and MCP integrations.
PayAI Network
ActiveSolana-first x402 payment facilitator enabling usage-based, machine-to-machine payments for AI agents.
MCP
2Universal Crypto MCP
ActivePlugin-based monorepo MCP: EVM+Solana wallets, DEX aggregation, x402 payments, CEX trading, market data, bridges.
Hashnet MCP Server
ActiveHashgraph Online MCP for agent discovery, chat, registration, workflows, and Hedera agent interactions.
Agent Framework
1Agent Launchpad
1Developer Tool
1Security Tool
1Skill Repo
1Wallet Infrastructure
1Other standards
Reference
QuestionsWhat people ask about this pageShowHide
Questions people ask about A2A: agents delegating to agents
- How many projects implement Agent2Agent?
- 14 live listings declare it as of 2026-10-15, spread across api / sdk 3, payment rail 3, mcp 2, agent framework 1. A declaration is recorded from the project's own materials — it is the floor of adoption, not a measurement of it.
- Does declaring Agent2Agent mean it answers?
- No, and the gap is the point. Declaring costs nothing: a tag, a manifest line, a sentence in a README. Whether an endpoint actually responds is measured separately by daily checks, published per listing, and never folded into this count.
- Where is Agent2Agent defined?
- In the standard's own documents, not here: A2A protocol at https://a2a-protocol.org. Sato Hub records which listings implement it and what our checks observed; it does not author the standard and does not certify conformance.
- Are these implementations verified?
- Not by implementing the standard. 14 of the 14 carry a Sato Score — a 0–100 reading of how open, active and verifiable a project is — and 9 publish an install manifest. Neither is an audit, a security review, or a conformance certificate.
- Which of these are open source?
- 10 of 14: Agent Payments Protocol (AP2), Lucid Agents, Universal Crypto MCP, Nevermined, Emblem Agent Skills, PRXVT, Agently, Universal Commerce Protocol (UCP), Agent0 SDK, create-8004-agent.
- Which are actively maintained?
- 4 had a commit or release in the last 30 days: Bankr, Universal Crypto MCP, Nevermined, Hashnet MCP Server. Posts on X do not count. Activity is a recency signal, not a quality judgment.
- Which have an earned verification on Sato Hub?
- 8: Bankr, Agent Payments Protocol (AP2), Lucid Agents, Universal Crypto MCP, Emblem Agent Skills, PRXVT, Agently, Universal Commerce Protocol (UCP). An earned check is named as what was checked (install reproduced, endpoint probed, on-chain identity read, reviewed against evidence); none is a safety claim.
- Which run as MCP servers?
- 7: Agent Payments Protocol (AP2), Lucid Agents, Universal Crypto MCP, Emblem Agent Skills, Hashnet MCP Server, Agently, Universal Commerce Protocol (UCP).
- How is this list ranked?
- A2A is derived from Sato Hub's live records by a stated rule and ordered by Sato Score, a 0–100 measure of how open, active and verifiable each project is. It is not a quality ranking and declares no winner.
SourcesWhere the data comes fromShowHide
Sources — the standard itself, and the implementations' own repositories
Cite this pagePlain text, APA or BibTeXShowHide
Cite this page
Sato Hub. "A2A: agents delegating to agents." Sato Hub, updated 2026-10-15, accessed 2026-10-15. https://satohub.ai/standards/a2aData last refreshed 2026-10-15; this page is rebuilt daily. Citations carry the date so a reader can tell which snapshot a claim came from. Catalog data is licensed CC-BY-4.0.
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