Agent to Agent Protocol (A2A) By Google

With the introduction of MCP Servers, it has changed the entire game of LLMs from just being able to give the response now to able to execute them with the help of tools. It may be:

• Querying data to get the data from database

• Executing an API call to make a POST request over a server

• Having AI do the stuff for you

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What is the Agent to Agent Protocol ?

A2A Protocol is a protocol launched by Google to maximise the benefits that we can get from Agentic AI. This is to make the agents be able to collaborate in a dynamic, multi-agent ecosystem across data systems and applications.

Here they have collaborated with more than 50 technology partners like Atlassian, Langchain, MongoDB, PayPal, CapGemini, KPMG, PwC, TCS, etc. This will now allow AI agents to communicate with each other, securely exchange information, coordinate actions on top of various enterprise platforms or applications. It is an open protocol that complements Anthropic’s Model Context Protocol (MCP), which provides helpful tools, and context to agents.

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How Does it Work ?

Consider an example where there is an agent made by me. My agent has the task to get the resume, analyse it , and return the best fit candidate for based on the Job Description and Job Profile. Now consider Apple is the recruiting partner, and they have created their own agent to get the work done for them and get the best candidate for them. This would be the flow now:

• Agent 1 finds the relevant job role, description and sends it to Agent 2.

• Agent 2 now checks all the resumes which match the job role and description given by Agent 1.

• After analysing and finding out the best candidate, it sends it to Agent 1.

• Agent 1 now sends handles the next step.

With this both the agents will be able to talk internally within themselves.

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Consider a real life example:

Dominos & Burger King have also started to create their own agent to make their work life easier for them. Zomato now as a platform which has both Dominos and Burger King will have their own agent which will take care for the work for them.

Consider a situation where the user says, ‘I want to eat a Pizza’, what will Zomato’s agent do ?. It needs to get the access to Domios’s Database to get the orders, but how will it get ? This will be done via the A2A Protocol. Same with the case when the user says, ‘ I want to eat a Whooper Burger Also’.

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How Do These Agents Discover Each Other ?

Making it more simple, How does Zomato’s agent discover that Dominos Agent has the following capabilities ?

They connect via OpenID Connect.

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What is OpenID Connect ?

Imagine you’re logging into a website, and instead of creating an account, you see a “Login with Google” button. You click it, and boom — you’re in. That is powered by OpenID Connect (OIDC).

📌 In Simple Terms:

OpenID Connect is a layer built on top of OAuth 2.0 that lets you log into apps using your existing account from providers like Google, Microsoft, Facebook,etc. It handles:

• ✅ Authentication (Who are you?)

• 🔐 Secure login without passwords

• 🔁 Passing user info between services

🔄 `/.well-known` in OIDC:

/.well-known is a standard path used by OIDC to automatically discover important configuration information about the identity provider like Google, AuthO, Okta,etc. In other terms, it’s where the identity provider publishes its OIDC configuration so that client apps know where to authenticate, get tokens, and fetch user info. Let’s take an example:

When an app wants to use Google as an identity provider, it goes to:

https://accounts.google.com/.well-known/openid-configuration

And gets back a JSON file like this:

For the agents, they connect via ./well-known/agent.json configuration in OpenID Connect.

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This is just the start of something new, there’s more to come. Checkout the GitHub link below for a sample code using A2A Protocol.

Source Code: https://github.com/google/A2A

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