What is the A2A protocol?
A plain-English guide to Agent2Agent for UK business owners
Quick answer: The Agent2Agent (A2A) protocol is an open standard that lets one AI agent find another agent or business, see what it can do, and send it a task. Google launched it in 2025 and it is now run by the Linux Foundation.
The simple version
Today a customer’s AI assistant can read your website, but it cannot easily ask your business anything. A2A fixes that. It gives agents a shared language, so a customer’s assistant can ask yours for opening hours, a quote or a booking and get a clear answer back.
Think of it as a telephone line for software. Your website is the shop window. A2A is the phone.
How it works, in three steps
- Discovery. Your business publishes an Agent Card, a small file at
/.well-known/agent-card.json. It says who you are, what you can do and how to reach you. - A request. The customer’s agent reads your card and sends a message to your endpoint, for example “is there a slot on Friday?”.
- A task and a result. Your system works out the answer, or starts a task such as a booking, and replies. Longer jobs can report progress as they go.
Messages are sent over ordinary secure web connections (HTTPS) in a standard format called JSON-RPC. You do not need special hardware.
Who needs it?
Most useful if customers might ask an AI assistant to do something with your business: book, quote, check stock or compare. Good fits include trades, clinics, salons, hospitality, professional services and online shops.
If you only run a brochure site with no bookings or quotes, you probably do not need A2A yet. A good website and clear structured data matter more first. Our AI agent readiness checklist shows the order to do things in.
What A2A does not do
A2A does not handle payments (that is AP2) and it does not connect an assistant to your databases and tools (that is MCP). See how the four standards fit together.
It also does not replace your website. It sits next to it.
What it costs us to set up
Our A2A implementation service starts from £2,500 and is quoted after a free call. We publish the Agent Card, build the endpoint, connect it to your booking or enquiry system and add limits and logging. You can see our own live card at heimdell-tech-ai.co.uk/.well-known/agent-card.json.
Frequently asked questions
Is A2A the same as MCP?
No. A2A connects AI agents to each other. MCP connects an AI assistant to tools and data. Many businesses use both.
Who created A2A?
Google announced it in April 2025 with a large group of partners. It was then handed to the Linux Foundation, so no single company owns it.
Do I need a developer to use it?
Yes, for now. It needs a published Agent Card and a secure endpoint connected to your systems. We build both for you.
Is it safe?
It can be. You decide which actions agents may take, which need a person to approve them, and every request is logged.
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