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Agent402 A2A Card Validator
x402
Agent402 A2A Card Validator is a paid API for AI agents from agent402.tools, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).
Validates an Agent Card JSON object against the A2A (Agent-to-Agent) specification, returning validity status, errors, warnings, and a summary
Price / call$0.002
Success—
StatusUnknown
How this service works
Validate an A2A (Agent2Agent protocol) Agent Card: required fields, skill shape, transport names, capability flags - spec v0.3 structural core. Returns errors, interop warnings, and a normalized summary (skills, interfaces, capabilities). Deterministic mini-A2A tooling - check a card before your agent trusts it.
Output
Returns a JSON object with a boolean 'valid' field, an 'errors' array listing any spec violations, a 'warnings' array for non-fatal issues, and a 'summary' object containing the agent name and skill count parsed from the card.
Example use cases
Pre-publish agent card check
“Before I publish my new research agent, validate this agent card JSON and tell me if it passes A2A spec — list any errors or warnings: {"name":"ResearchBot","skills":[{"id":"web-search","name":"Web Search"}]}”
Debugging a malformed agent card
“My agent card keeps getting rejected — can you run it through the A2A card validator and tell me exactly what's wrong with it? Here's the card JSON.”
Verifying skill count and agent name
“I just built an agent card with 5 skills defined — can you validate it and confirm the name and skill count look right in the summary?”
Technical details
Endpoint
POSThttps://agent402.tools/api/a2a-card-validateWhen to prefer
Use this endpoint when you need to verify that an Agent Card JSON document conforms to the A2A (Agent-to-Agent) specification before publishing or registering it. It is the right choice when debugging why an agent card is being rejected, or when building tooling that programmatically generates agent cards and needs to validate output. Prefer this over manual schema checking when you want actionable error messages and a parsed summary in one call.
Side effects
- Malformed JSON input returns validation errors listing structural issues
- Missing required A2A fields trigger error entries in the errors array
- Unknown or unsupported skill definitions may generate warnings
- Empty card object returns valid:false with descriptive errors
- Passing a JSON string instead of object is supported but malformed strings fail
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| card | object | the Agent Card JSON (object or JSON string) |
Output
Schema · Response
{
"type": "json",
"example": {
"valid": true,
"errors": [],
"summary": {
"name": "Sample Weather Agent",
"skillCount": 1
},
"warnings": []
}
}Tags
x402
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