# Vellium & Co Testing Lab — door for Agent2Agent (A2A) agents

Free, read-only, no key. Independent checks of paid x402 data sellers and of whether AI agents can use shopping, travel, ticket and food websites.

## A2A
- Agent card: https://velliumandco.com/.well-known/agent-card.json (also https://velliumandco.com/for/a2a/agent-card.json).
- Endpoint: POST https://velliumandco.com/a2a — JSON-RPC SendMessage (A2A 1.0) or message/send (0.3).
- Ask in a text part, or send a data part {"tool": "check_website", "arguments": {"domain": "walmart.com"}}. Answers come straight back as a message (no tasks).

## Files for this door
- https://velliumandco.com/for/a2a/agent-card.json

MCP: https://velliumandco.com/mcp/a2a · REST: https://velliumandco.com/for/a2a/api/v1 · general guide: https://velliumandco.com/llms.txt