MCP vs A2A vs ACP vs...

Comparing agent protocols

2025-05-23 MCP Summit

What are we

talking about?

12+ agent protocols

A disclaimer

What the **** do I know?

A quick plug

workflow_as_mcp(agent)

get_tools_from_mcp_url(url)

An incredibly

useful paper

A Survey of AI Agent Protocols, Yang et al 2025

arxiv.org/abs/2504.16736

Protocols covered

  • MCP
  • A2A
  • AC(onnect)P
  • AC(ommunication)P
  • ANP
  • AITP
  • Agora
  • PXP
  • LOKA
  • CrowdES
  • SPP
  • LMOS
  • AP
  • WTF
  • LOL

What is the vision?

What is the reality?

xkcd.com/927

Taxonomy of agent protocols

What does Context-Oriented mean?

What does Inter-Agent mean?

Agents.json

./well-known ➡️ agents.json

docs.wild-card.ai/agentsjson/introduction

A2A:

Agent to Agent Protocol

An inter-agent protocol from Google

google.github.io/A2A/

A2A's perspective

Inter-agent is hard and MCP doesn't want that heat

ANP:

Agent Network Protocol

It's A2A but on the blockchain!

agent-network-protocol.com

AITP:

Agent Interaction & Transaction Protocol

It's (also) A2A but on the blockchain!

aitp.dev/vision

ACP x2

  1. Agent Connect Protocol (Cisco)
  2. Agent Communication Protocol (IBM)

ACP:

Agent Connect Protocol

It's A2A but from Cisco!

spec.acp.agntcy.org

ACP's perspective

You have to think bigger than MCP is thinking right now

ACP:

Agent Communication Protocol

It's A2A but from IBM!

agentcommunicationprotocol.dev

Agora

It's neat!

agoraprotocol.org

Domain specific protocols

Human-Agent interaction protocols

  1. PXP
  2. LOKA

Robot-Agent interaction protocols

  1. CrowdES
  2. Spatial Population Protocols

LMOS:

Large Model Operating System

It's A2A but from IBM (again)!

eclipse.dev/lmos

Agent Protocol

It's agents.json (again)!

agentprotocol.ai

End of tour

"Within context-oriented interactions, interactive tools can be regarded as low-autonomy agents. Conversely, in agent-to-agent interactions, the communicating agents can also be viewed as tools with higher autonomy, designed to accomplish specific intelligent tasks."

– Yang et al (2025)

What MCP lacks

relative to other protocols

  1. Async?
  2. Renegotiation?
  3. ...?

MCP stands alone

in adoption

(Users') Attention Is All You Need

MCP plus...?

Does MCP need other protocols?

So MCP is perfect?

Nope.

A registry

I mean of course I think that.

Under construction!

A (better) authorization model

Reputation

What are "download counts" for an agent?

Let's find out what's next, together

You can follow me on BlueSky:

🦋 @seldo.com