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The Agent2Agent Protocol (A2A)

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Re: The Agent2Agent Protocol (A2A)

#111

Post by Nav_Panel »

AndrewKemendo wrote: post #30

These protocols are to put handlers between you and your own data so they can sell it back to you via “search.” Companies who are betting their future on LLMs realized a few years ago that the data they can legally use is the only long term difference between them, aka “moat.” Now that everyone has more or less the same public data access, and a thin compute moat is still there, the goal is to transfer your private t…

This is insanely cynical. The optimistic version is that many teams were already home-rolling protocols like A2A for "swarm" logic. For example, aggregation of financial data across many different streams, where a single "executive" agent would interface with many "worker" high-context agents that know a single stream.

I had been working on some personal projects over the last few months that would've benefitted enormously from having this kind of standard A2A protocol available. My colleagues and I identified it months ago as a major need, but one that would require a lot of effort to get buy-in across the industry, and I'm happy to see that Google hopped in to do it.

Re: The Agent2Agent Protocol (A2A)

#112

Post by mindcrime »

behnamoh wrote: post #49
zellyn wrote: post #3

It’s frustratingly difficult to see what these (A2A and MCP) protocols actually look like. All I want is a simple example conversation that includes the actual LLM outputs used to trigger a call and the JSON that goes over the wire… maybe I’ll take some time and make a cheat-sheet. I have to say, the endorsements at the end somehow made this seem worse…

It seems companies figured introducing "protocols" or standards helps their business because if it catches on, it creates a "moat" for them: imagine if A2A became the de facto standard for agent communication. Since Google invented it and already incorporated in their business logic, it would suddenly open up the entire LLM landscape to Google services (so LLMs aren't the end goal here). Microsoft et al. would then e…

or adopt Google's.

Which is an open standard that is Apache licensed[1]. That's no moat for Google. At best it's a drainage ditch.

[1]: https://github.com/google/A2A

Re: The Agent2Agent Protocol (A2A)

#113

Post by samuell »

So now we are going towards using models to more efficiently store information, and let them talk to each other, instead of moving massive datasets around, as briefly outlined in 2023 in [1] & [2] (although I would anticipate that linked data might help here too)?

[1] https://livingsystems.substack.com/p/the-future-of-data-less...

[2] https://livingsystems.substack.com/p/will-data-served-as-lan...

Re: The Agent2Agent Protocol (A2A)

#114

Post by mindcrime »

pjmlp wrote: post #54
srameshc wrote: post #37

Earlier quoted context omitted.

That looks interesting from abstract. Can you please explain how these two can be interconnected ?

Back in the late 90's, during one of the previous AI waves, there was this idea of autonomous agents, where one would communicate by sending code snippets or bytecode if using something like Java, which would trigger tasks on remote agents that would process those requests on their own somehow, and the transmited code snippets would be extensible logic. As far as I can remember, never really left the research lab, wi…

Later renamed as D'Agents[1]. Still never got any serious industry adoption as far as I know, but I guess the code is still out there if somebody wanted to do something with it.

[1]: https://wiki.tcl-lang.org/page/D%27Agents+%28formerly+Agent+...

Re: The Agent2Agent Protocol (A2A)

#115

Post by nlarew »

zurfer wrote: post #55

My current understanding: MCP - exposes prompts, resources and tools to a host, who can do whatever they like A2A - exposes capability discovery, tasks, collaboration?/chat?, user experience discussions (can we embed an image or or a website?). High-level it makes sense to agree on these concepts. I just wonder if we really need a fully specified protocol? Can't we just have a set of best practices around API endpoin…

> Can't we just have a set of best practices around API endpoints/functions? Like, imo we could just keep using Rest APIs and have a convention that an agent exposes endpoints like /capabilities, /task_status ...

To make this work at scale we all need to agree on the specific routes names, payloads, behaviors, etc. At that point we have defined a protocol (built on top of HTTP, itself a lower level protocol).

Re: The Agent2Agent Protocol (A2A)

#116

Post by kristopolous »

mlenhard wrote: post #76
zellyn wrote: post #3

It’s frustratingly difficult to see what these (A2A and MCP) protocols actually look like. All I want is a simple example conversation that includes the actual LLM outputs used to trigger a call and the JSON that goes over the wire… maybe I’ll take some time and make a cheat-sheet. I have to say, the endorsements at the end somehow made this seem worse…

I was in the same boat in regards to trying to find the actual JSON that was going over the wire. I ended up using Charles to capture all the network requests. I haven't finished the post yet, but if you want to see the actual JSON I have all of the request and responses here https://www.catiemcp.com/blog/mcp-transport-layer/

I had never heard of charles ... (https://www.charlesproxy.com/) I basically wrote a simple version of it 20 years ago (https://github.com/kristopolous/proxy) that I use because back then, this didn't exist ... I need to remember to toss my old tools aside

Re: The Agent2Agent Protocol (A2A)

#117

Post by Nav_Panel »

cowpig wrote: post #109

I don't totally understand why we need an additional layer of abstraction over MCP at this point. Why can't an agent just be an MCP server? What is the fundamental difference between an MCP server "tool" and an agent "capability"? This kind of feels to me like someone at google saw how successful MCP was becoming and said "we need something like that". I feel the same way about OpenAI's Agent SDK. I think the word "A…

A2A isn't a layer of abstraction over MCP, it functions in parallel and they complement each other. MCP addresses the Agent-to-Environment question, how can Agents "do things" on computers. A2A addresses the Agent-to-Agent question, how can Agents learn about other Agents and communicate with them. You need both.

You CAN try and build "the one agent that does everything" but in scenarios where there's many simultaneous data streams, a better approach would be to have many stateful agents handling each stream via MCP, coupled with a single "executive" agent that calls on each of the stateful agents via A2A to get the high-level info it needs to make decisions on behalf of its user.

Re: The Agent2Agent Protocol (A2A)

#119

Post by evacchi »

simonw wrote: post #19

I just published some notes on MCP security and prompt injection. MCP doesn't have security flaws in the protocol itself, but the patterns it encourage (providing LLMs with access to tools that can act on the user's behalf while they also may be exposed to text from untrusted sources) are rife for prompt injection attacks: https://simonwillison.net/2025/Apr/9/mcp-prompt-injection/

we also recently published our approach on MCP security for mcp.run. Our "servlets" run in a sandboxed environment; this should mitigate a lot of the concerns that have been recently raised.

https://docs.mcp.run/blog/2025/04/07/mcp-run-security

Re: The Agent2Agent Protocol (A2A)

#120

Post by mlenhard »

kristopolous wrote: post #116
mlenhard wrote: post #76

Earlier quoted context omitted.

I was in the same boat in regards to trying to find the actual JSON that was going over the wire. I ended up using Charles to capture all the network requests. I haven't finished the post yet, but if you want to see the actual JSON I have all of the request and responses here https://www.catiemcp.com/blog/mcp-transport-layer/

I had never heard of charles ... ( https://www.charlesproxy.com/ ) I basically wrote a simple version of it 20 years ago ( https://github.com/kristopolous/proxy ) that I use because back then, this didn't exist ... I need to remember to toss my old tools aside

Yeah, at its core it's just a proxy, so there are a lot of other tools out there that would do the job. It does have a nice UI and I try to support projects like it when I can.

I'll check out your proxy as well, I enjoy looking at anything built around networking.

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