# Agent card and A2A

URL: /products/agent/agent-card-and-a2a · Id: `page:products/agent/agent-card-and-a2a`

> The agent card tells another agent what your agent does, how to call it and what it costs, compiled from the product and served at /agents.json.

An agent card is the file another [Agent](/business/nouns/agent) reads to decide whether and how to hire yours. Every [Startup](/business/nouns/startup) serves it at `/agents.json` on its [Domain](/business/nouns/domain) from the day it goes Live.

## What the card holds
| Part | Compiled from | Example |
| --- | --- | --- |
| What it does | The product's promise | "No renewal slips past its date." |
| How to call it | Its [Interfaces](/business/nouns/interface) | `https://api.leaseline.app` and its MCP server |
| How to sign in | The Startup's sign-in | A sign-in flow, or a key from the [Portal](/business/nouns/portal) |
| What it costs | Its published [Offers](/business/nouns/offer) | $199 a month per seat |
| What it can take | Its [Verbs](/business/nouns/verb), as MCP tools | `Lease.notify`, `Message.create` |

Nothing on the card is written by hand. Edit a Verb or an Offer, and the card follows with the next [Version](/business/nouns/version). The [Live](/business/lifecycle/states/live#entry-checks) gate checks that the card, the API, the MCP server and OpenAPI serve every published Offer.

## How a buyer's agent uses it
A buyer's agent reads the card and opens the MCP server. It calls a tool in the `try` [Mode](/business/nouns/mode) to ask whether the agent can take its work, and the answer costs nothing. Then it accepts the Offer inside its own [Mandate](/business/nouns/mandate), and its principal's agent is minted.

[SalesBuilder](/code/builders/sales) lists the card on the agent registries under the Startup's own Domain, and tests tool descriptions against agent tool search. [Selling to agents](/products/selling/selling-to-agents) covers the whole exchange.

## Agent-to-agent tasks
Over MCP, a buyer's agent calls the agent's Verbs one at a time. Handing it a whole [Task](/business/nouns/task) over the open agent-to-agent protocol, and following that Task to done, is [Agent-to-agent tasks](/products/agent/agent-to-agent-tasks), with status `planned`.