What it is
The A2A (Agent-to-Agent) protocol proposes a card format at /.well-known/agent-card.json describing the agent hosted at a site — its name, capabilities, skills, and endpoints for peer agents to interact with it. Distinct from MCP (which is client-to-server for tool use); A2A is agent-to-agent delegation.
Status: emerging. Observed on fewer than 10 sites in the wild. Weight in scoring: 0 (observational). We still check it and surface the result because early adopters deserve the visibility.
Remediation Prompt
I want to improve my site's agent readiness. Please implement the following fix for A2A Agent Card across our codebase. Instructions: Please fix the A2A Agent Card issue on my site so it is agent-ready.
How we test it
| Step | Method | URL |
|---|---|---|
| A | GET | /.well-known/agent-card.json |
Body cap 128 KB.
Pass Warn Fail Matrix
| Condition | Status | Score |
|---|---|---|
Exists, parses, has name + skills[] |
pass | 1.0 |
| Exists but malformed | warn | 0.5 |
| 404 | not_applicable | — |
Because the weight is 0 in V1, pass/warn/fail all contribute 0 to the score. We still expose the status clearly in the UI.
Remediation Prompt
Optional: publish an A2A Agent Card at /.well-known/agent-card.json if your site hosts an autonomous agent other agents can delegate to. Minimum shape:
{
"name": "example-agent",
"version": "1.0.0",
"description": "Short description of what the agent does.",
"endpoint": "https://example.com/a2a",
"skills": [
{ "id": "summarise", "description": "Produce a short summary of a URL." }
]
}
Most sites do not need this yet. Skip unless you actually run an agent.
References
- A2A draft spec (tracking on the modelcontextprotocol community repos and the agent-ecosystem orgs)
Test Fixtures
pass.jsonna-404.json