An Agent Card is a JSON file, published at /.well-known/agent.json, that tells AI agents who you are, what you can answer, and what you can do: your business identity, your capabilities, your service endpoints, and the authentication a machine needs to work with you. It's the discovery layer of the Agent2Agent (A2A) protocol Google launched on April 9, 2025, now governed by the Linux Foundation.
Think of it as the heir to the meta tag. And before the anxiety sets in: you almost certainly don't need one this quarter. The reason to understand Agent Cards now is timing, because the businesses that recognize the moment this changes will collect a head start measured in years, not weeks.
What is an Agent Card, in plain English?
Today, when an AI assistant wants to know something about your business, it scrapes your website and guesses. It reads your pages the way a hurried stranger would, infers what you offer, and hopes the information is current.
The Agent Card replaces scrape-and-guess with call-and-ask. It's a structured file that declares, in a format machines parse natively: this is who we are, these are the specific things we can answer or do (check availability, quote a price, book an appointment), here's where to send the request, and here's the security we expect. Under A2A, an orchestrating agent, say, the assistant a customer asked to find and book a plumber, reads these cards to discover which services exist and decide which one to use.
The location matters as much as the contents. The card lives at a fixed, standardized address on your domain (the /.well-known/ convention, RFC 8615), so an agent doesn't hunt for it. One known door, every site, same place. Your website tells machines what's on your pages. The Agent Card tells them what your business can do. That's the whole shift in one line.
Why call it the heir to the meta tag?
Because the selection mechanics rhyme. Early security research from Trustwave, surfaced in Stan Ventures' analysis of A2A, found that when a host AI decides which agent to use for a task, the card's name and description fields carry the most weight. Sound familiar? It's the meta title and meta description all over again: a short text pair that decides whether you get chosen, except the reader is an AI selecting a data source, not a human scanning a results page.
The parallel extends to the failure modes. A vague description loses selections the way a vague meta description loses clicks. And there's a sharper trap with no classic-SEO equivalent: the capabilities list is exhaustive as far as the agent knows. Every capability you don't declare is a query you silently can't answer. A card that lists booking but not pricing means the agent asking for quotes never calls you, no matter how good your prices are.
Dileep Thekkethil of Stan Ventures put a flag in the ground on where this goes: "It won't be long before SEO audits start with: 'Where's your Agent Card?'" Our title puts a year on his prediction, and the year is our bet, not his. What we'd defend either way: the question enters the audit template long before most businesses have an answer.
What does one look like?
Here's an example card for a fictional Jacksonville plumbing company. Fictional is the operative word: the business, domain, and endpoints are invented for teaching. This is yours to adapt.
{
"name": "Bold City Plumbing",
"description": "Licensed residential plumbing in Jacksonville, FL. Same-day emergency repair, water heater replacement, repiping, and drain service. Availability, quotes, and booking by request.",
"url": "https://boldcityplumbing.example.com/agent",
"provider": { "organization": "Bold City Plumbing LLC" },
"version": "1.0.0",
"authentication": { "schemes": ["bearer"] },
"defaultInputModes": ["text"],
"defaultOutputModes": ["text"],
"skills": [
{
"id": "check-availability",
"name": "Check appointment availability",
"description": "Returns open service windows for a date and Jacksonville-area zip code."
},
{
"id": "quote-water-heater",
"name": "Water heater replacement quote",
"description": "Returns an installed-price range for standard and tankless models."
},
{
"id": "book-service",
"name": "Book a service call",
"description": "Books a confirmed appointment from name, address, phone, and issue."
}
]
}
Walking the fields that earn their bytes:
nameanddescription: the selection pair. Note the description reads like a great meta description: services named plainly, area stated, capabilities implied. "Your trusted partner for plumbing excellence" would lose to this every time, for the same reason it already loses in search results.urlandauthentication: where the agent connects and how. The card promises; the endpoint behind it has to deliver, fast and securely, which is its own subject: whether your site is agent-ready at all.skills: the capability list, one entry per thing an agent can ask of you. Specific descriptions matter here too; "Returns an installed-price range" tells the orchestrator exactly which customer questions route to you.version: cards evolve with the spec, and the spec is young. Date and version everything.
If the shape reminds you of schema markup, good instinct: structured data is today's version of describing yourself to machines. The card is what it grows up into: schema describes, the Agent Card transacts.
Does your business need one this quarter?
Almost certainly not, and we'd rather say that plainly than sell you a JSON file. A2A adoption is early: the protocol has over 150 backing organizations, but most announced integrations are commitments rather than running deployments, and the businesses transacting through agents today are pilots, not your local market. A Jacksonville plumber who ships an Agent Card this month has built a beautiful door onto a street with no foot traffic.
Here's the four-question test that tells you when the answer flips. Score a point for each yes:
AGENT CARD READINESS TEST
1. Do customers already transact with you online,
without a phone call? (booking, ordering, quoting)
2. Is your first-party data structured enough that
software could answer "do you have X on Thursday?"
(calendars, inventory, price lists in systems,
not in someone's head)
3. When you ask ChatGPT or Perplexity about your
category in your market, do assistants already
answer with specific businesses?
4. Has any direct competitor published a card at
/.well-known/agent.json?
0 yes: revisit in a year.
1-2: do the groundwork, skip the card.
3-4: the window is open. Move.
The groundwork is the part that pays regardless of timing: structured data, clean and fast endpoints, a site that parses. All of it serves how AI systems evaluate you today, and it's the same foundation a card will sit on later. Question 4 deserves a standing reminder in your calendar, because it's the one that changes overnight.
We covered the strategic tension behind all this in Google's own guidance on AI search: fundamentals first, agent layer prepared, hacks skipped. The Agent Card is the clearest artifact of that second half.
The check worth doing tonight
Two URLs: yoursite.com/.well-known/agent.json and the same path on your biggest competitor's domain. Almost certainly both return nothing, and that's today's normal. The night one of them doesn't, the clock in your market has started, and you'll be one of the few owners who knew what they were looking at.