---
title: 'Agent Card'
description: "An A2A discovery document that describes an agent's identity, supported interfaces, capabilities, skills, and security schemes."
canonical_url: 'https://darkfactory.dev/glossary/agent-card'
markdown_url: 'https://darkfactory.dev/glossary/agent-card.md'
collection: glossary
date_published: '2026-08-03T00:00:00-04:00'
date_modified: '2026-08-26T00:00:00-04:00'
---

# Agent Card


## Definition

An **Agent Card** is the discovery document an Agent2Agent Protocol server publishes to describe an agent. It identifies the agent and provider, lists supported interfaces and optional capabilities, describes skills, and declares the security schemes a client must use. A client reads the card before deciding how to connect and whether the agent appears relevant to a task.

The current A2A specification also supports signatures and an authenticated extended card. Signatures can establish who signed a particular representation when verification is configured correctly. An extended card can disclose additional information only after authentication. Neither mechanism turns marketing claims into measured capability.

## Treat it as an advertisement

Cards can be stale, overly broad, or published by an untrusted endpoint. Discovery should therefore feed a separate trust decision. Verify server identity, card signature where required, protocol version, security scheme, freshness, and local delegation policy before sending data or work.

## Distinguish it from nearby terms

An API description documents callable operations. An MCP server exposes tools, resources, or prompts to an AI application. An A2A Agent Card advertises an independent agent service and the tasks it claims to handle. It is not a runtime authorization token or evidence that a skill succeeds.

## Check your understanding

An Agent Card says an agent can process payroll and supports OAuth. May your orchestrator send employee records? The card answers discovery and connection questions. Local identity, authorization, data-handling policy, risk, and capability evidence still decide whether delegation is allowed.

## Related factory areas

- [Tools & project interfaces](https://darkfactory.dev/factory/tools-interfaces)
- [Security, privacy & software supply chain](https://darkfactory.dev/factory/security)

## Evidence and further reading

- [Agent2Agent Protocol Specification](https://a2aproject.github.io/A2A/latest/specification/)