# A2A agent card

Declares an agent this site operates, for agent-to-agent work.

**[Trust](/docs/trust)** · checked once per host (item type `agent_card`) · 4 checks that can fail it

A card is how another agent discovers what this site's agent can do and how to reach it. Crawlers already probe for the path, so a card published in the pre-1.0 shape is a live present-but-wrong surface.

## Adoption

**Early pilots** (L1) — standard inside enterprise agent platforms, still rare on the open web

Named early adopters exist, behind flags or trials. Nothing has been independently measured yet. Direction of travel: ▲ rising, as of 2026-07-28.

GA inside Microsoft, AWS and Google agent platforms with 150+ supporting organisations, but no verifiably identified public open-web card publisher. Crawler logs show agents requesting the path anyway.

| Adopter | Depth | Evidence |
|---|---|---|
| Microsoft (Copilot Studio, Azure AI Foundry) | default-on | [linuxfoundation.org](https://www.linuxfoundation.org/press/a2a-protocol-surpasses-150-organizations-lands-in-major-cloud-platforms-and-sees-enterprise-production-use-in-first-year) |
| AWS (Bedrock AgentCore Runtime) | production | [linuxfoundation.org](https://www.linuxfoundation.org/press/a2a-protocol-surpasses-150-organizations-lands-in-major-cloud-platforms-and-sees-enterprise-production-use-in-first-year) |
| Google (Gemini Enterprise) | production | [a2a-protocol.org](https://a2a-protocol.org/latest/announcing-1.0/) |
| SAP, Salesforce, ServiceNow, Cisco, IBM | announced | [a2a-protocol.org](https://a2a-protocol.org/latest/announcing-1.0/) |

## What we check

Absence is never a finding: every check below runs only once `agentCardPresent` is true, so a site that has not
adopted this is not assessed on it and appears in no report.

| Check | Kind | Raises | On whose authority |
|---|---|---|---|
| `agentCardInvalidJson` | high severity | conformance, usability | specification (A2A v1.0.0) |
| `agentCardMissingFields` | high severity | conformance, usability | specification (A2A v1.0.0) |
| `agentCardEndpointNotA2A` | high severity | usability | specification (A2A v1.0 §5.3 (Method Mapping Reference), §11.3.1) |
| `agentCardInvalidSignature` | high severity | conformance, usability | specification (A2A v1.0.0) |
| `agentCardEndpointUnverified` | informational | nothing | Lumar readiness profile |

## Examples

These are the fixtures the test suite runs through the real collector, not snippets written for a document.

- Correct: `test/e2e/test-pages/trust/correct.agent-card.json`
- Present but wrong: `test/e2e/test-pages/trust/issues.agent-card.json`

## Specifications

| Document | Revision | Kind |
|---|---|---|
| [A2A protocol specification](https://a2a-protocol.org/latest/specification/) | v1.0.0 | specification |

Last re-read against the published documents: 2026-08-26.