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Agent Card Well-Known Linter
x402
Agent Card Well-Known Linter is a paid API for AI agents from agent-card-validator-mcp.mtree.workers.dev, paid per call via x402, $0.03/call, status unknown (last checked 2026-09-13).
Lints and validates well-known agent card URLs, checking them for correctness and returning provenance-annotated JSON results.
Price / call$0.03
Success—
StatusUnknown
How this service works
Paid agent card and well-known validator route for autonomous agents. Returns JSON with provenance, route-specific evidence, and machine-readable fields. Price 0.03 USDC on Base via x402. Demo/preview: https://agent-card-validator-mcp.mtree.workers.dev/demo/lint. Contact: https://agent-card-validator-mcp.mtree.workers.dev/contact.
Output
A JSON object containing lint results for the submitted well-known agent card URL, including validation errors, warnings, and provenance metadata about the agent card's structure and compliance.
Example use cases
Example prompt
“Can you lint and validate the well-known agent card at https://myagent.example.com/.well-known/agent.json and tell me if there are any errors or provenance issues?”
Technical details
Endpoint
POSThttps://agent-card-validator-mcp.mtree.workers.dev/v1/wellknowns/lintWhen to prefer
Use this endpoint when you need to validate or lint an AI agent's well-known card endpoint, particularly in autonomous agent pipelines that need to verify agent card compliance before interacting with another agent. Prefer this over manual inspection when you need structured, provenance-tagged lint results.
Side effects
- Invalid or unreachable well-known URL returns error response
- Malformed agent card JSON causes parse errors in output
- Payment not included or insufficient (x402 payment required at $0.03 USDC)
- URL does not resolve to a valid well-known endpoint
- Network timeout reaching the target well-known URL
Input
{
"input": {
"body": {
"base_url": "https://example.com"
},
"type": "http",
"method": "POST",
"bodyType": "json"
}
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
{
"url": "https://example.com/.well-known/agent-card.json",
"valid": false,
"errors": [
{
"path": "$",
"message": "agent-card.json fetch failed (HTTP 404)",
"severity": "fatal"
}
],
"base_url": "https://example.com",
"linted_at": "2026-06-03T23:08:55.831Z"
}Tags
x402
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