An A2A Agent Card published at /.well-known/agent-card.json is how one agent discovers another's identity, skills, and capabilities — and it's the layer AP2 and x402 ride on. This tool validates the card against the A2A v1.0 shape, checks the signed-card signatures block, and confirms an AP2 / x402 extension is declared correctly. Produces a §4 compliance_control OpenChainGraph artifact.
/.well-known/agent-card.json. An example is pre-loaded; the second button loads a signed card.Copy this paragraph into Claude, OpenClaw, or any MCP-aware agent to run this exact tool, with this sample, and verify the artifact.
Run the AINumbers MCP tool `verify_a2a_agent_card`. Task: Validate an A2A agent-card.json against the v1.0 shape: identity fields, capabilities, extensions (AP2/x402), input/output modes, skills, provider, signed-card JWS block.
Call it with arguments: {"policy_parameters":{"agent_card":{"name":"Test Agent","description":"A test payment agent","url":"https://agent.example.com","version":"1.0","protocolVersion":"1.0","capabilities":{"streaming":false,"pushNotifications":false,"extensions":[]},"defaultInputModes":["text/plain"],"defaultOutputModes":["application/json"],"skills":[{"id":"pay","name":"Payment","description":"Execute payments","tags":["payment"]}]}}}
Verify before trusting: call `verify_execution_hash` on mcp.ainumbers.co (https://mcp.ainumbers.co/mcp) with the parameter `claimed_hash` set to the returned `execution_hash`, passing the full artifact the run returned (the object containing `policy_parameters` + `output_payload` + `execution_hash`; equivalently `policy_parameters` + `output_payload` with `claimed_hash`), not the bare hash string.
Return the ledger link https://ledger.ainumbers.co/ so a human can re-verify without contacting us.
PII rule: All inputs are processed locally in your browser. No data is transmitted. Do not enter real personal data — use synthetic or anonymised inputs only.
Open the tool with the sample prefilled: https://ainumbers.co/chaingraph/art-25-a2a-agent-card-validator.html#p=v1.H4sIAAAAAAAA_wGKAXX-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