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agentx.sale A2A/MCP Protocol Card Linter
x402
agentx.sale A2A/MCP Protocol Card Linter is a paid API for AI agents from agentx.sale, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-21).
Validates an agent.json or server-card.json URL against the A2A/MCP protocol spec and returns drop-in patched JSON fixes
Price / call$0.02
Success—
StatusUnknown
How this service works
A2A / MCP protocol card lint: validate agent.json / server-card.json and return drop-in patched JSON fixes
Output
Returns a linting verdict indicating whether the agent.json or server-card.json at the given URL is valid, a list of specific spec violations or missing fields, and a drop-in patched JSON object with the issues resolved that can be used as a direct replacement.
Example use cases
Fix broken agent manifest before launch
“My agent.json at https://myservice.ai/.well-known/agent.json isn't passing A2A validation — can you lint it and give me the corrected JSON I can drop straight in?”
MCP server card compliance check
“Check whether my MCP server card at https://api.example.com/server-card.json is spec-compliant and show me exactly what needs to change.”
CI pipeline agent protocol validation
“Before I deploy, can you validate the agent.json hosted at https://staging.mybot.dev/agent.json and return a patched version if there are any protocol errors?”
Technical details
Endpoint
GEThttps://agentx.sale/x402/protocol-lint?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need automated, spec-aware linting of A2A agent.json or MCP server-card.json files with actionable patched output. It goes beyond a generic JSON schema validator by understanding the A2A/MCP protocol semantics and returning ready-to-use fixed JSON, making it ideal for CI pipelines, pre-deployment checks, or agent-readiness workflows.
Side effects
- URL is unreachable or returns non-200 — endpoint cannot fetch the card
- URL points to non-JSON content — parse error returned
- JSON is not recognizable as an agent.json or server-card.json format — schema mismatch error
- Rate limiting or payment failure for the x402 micropayment ($0.02 USDC)
- URL missing from query params — required parameter validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"fixes": [],
"valid": true
}
}Tags
x402
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