The Protocol Caught Up

Why legibility now lives at the protocol level. People understand you. Models cite you. Agents hire you

Katya Shalel

For two years I have been writing about the same idea under different names. A neutral decision layer. A callable layer. Share of model. The claim was always this: in the next economy, the winner is not the one with the biggest shelf, but the one whose judgment other systems can call.

This spring the industry gave that idea a name and a file format.

What happened

A2A, a protocol developed by Google and handed to the Linux Foundation, lets AI agents discover each other, delegate tasks, and exchange results. The discovery mechanism is called an Agent Card: a public JSON file that says, in machine-readable form, who I am, what I can do, where to call me, and where my responsibility ends.

Around it, a stack assembled fast. UCP standardizes commerce between agents, built with Shopify, Etsy, Wayfair, Target and Walmart. AP2 handles payment authorization. By spring 2026 A2A was in production across more than 150 organizations through Azure AI Foundry, Amazon Bedrock AgentCore and Salesforce.

Read that list again. When Google, Microsoft, Amazon, Salesforce and the largest retailers converge on one protocol within a year, that is not a trend. That is infrastructure being poured.

Why this is a legibility story

I define legibility as the work of making yourself readable to the systems that now mediate attention, trust and money. Most founders still think this means content. Publish essays, get cited, win share of model inside the language models that answer questions about your market.

An Agent Card is the same act one layer deeper. It is not content about your product. It is your product describing itself to machines, in a format machines are built to trust. A profile makes you findable by models. An Agent Card makes you callable by them.

This is the part I did not fully see when I coined my own terms. Legibility has a stack, like everything else.

Layer one: people understand you.

Layer two: models cite you.

Layer three: agents hire you.

Layer one is positioning. Layer two is schema, essays, entities, share of model. Layer three is a published skill, an endpoint, a declared boundary of responsibility.

Layer three is protocol-level legibility.

It is the difference between being quoted and being hired.

The uncomfortable symmetry

Here is what makes this personal. The scenario “a marketplace agent calls a skin analysis sub-agent over an API” has been on the SKINBOT site for months. The essay about a router of sub-agents was written before we had ever used the word A2A. I would like to claim foresight. The honest version is stranger.

I thought I was describing a product architecture. Looking back, I was describing an economic architecture that did not yet have a protocol.

That is the real argument for doing the legibility work early. Not vanity, not personal branding. When a standard arrives, the companies that already wrote down what they do, in plain declarative terms, can adopt it in days. Everyone else first has to figure out what they are.

What a founder should do with this

Not everything needs an Agent Card this quarter. But every founder should be able to answer the question the Card asks, because it is the oldest question in business wearing a new file extension:

What exactly do you do, who is allowed to call you, and where does your responsibility end?

Every protocol eventually asks the same question: what exactly are you?

The companies that already know the answer adopt the protocol. The rest first have to discover themselves.

The protocol caught up. The question was always there.