Publisher repairs

For JSON-RPC, publish the exact HTTPS application route that accepts A2A POST requests. A homepage, documentation page or normal resource such as /weather is not a substitute. Check that your application and reverse proxy route the same address.

For HTTP+JSON, advertise the A2A service base URL. LocalMark derives the standard read-only task route: /v1/tasks/{id} for A2A 0.3, or /tasks/{id} for A2A 1.0. Avoid duplicating an existing /v1 prefix.

A standard A2A “task not found” error may correctly use HTTP 404. A generic missing webpage is different. Implement real task lookup and its standard error behavior; do not return a hard-coded success for LocalMark.

Compare the request method shown on each listing with the method your application and reverse proxy allow. JSON-RPC uses POST. HTTP+JSON task lookup uses GET on the version-specific task route.

If the observed Allow header contains only GET, HEAD for a declared JSON-RPC route, the card may point to a website or a read-only REST resource. Advertise the real A2A route, or implement the declared A2A interface there. Do not simply allow POST on an unrelated handler.

Keep authentication, authorization and TLS checks in place. A method being accepted is not protocol confirmation; the handler must actually speak A2A.

A2A 0.3 JSON-RPC uses tasks/get; A2A 1.0 uses GetTask. Declare the version your service implements and implement its task lookup and missing-task error using your A2A framework’s real task handling.

Both versions use a request shaped like the example below, with the version-specific method. Use a task ID that does not exist. This is a request example, not a response to copy into your server.

{
  "jsonrpc": "2.0",
  "id": "publisher-readonly-check",
  "method": "tasks/get",
  "params": {"id": "nonexistent-example-task"}
}

For A2A 1.0, change the method to GetTask and send A2A-Version: 1.0. A generic JSON-RPC error alone does not confirm A2A. The probe never sends a message or creates a task.

Match the Agent Card schema to the protocol version your service implements. A2A 0.2 and 0.3 use top-level protocolVersion, url and preferredTransport; optional additionalInterfaces entries use transport. A2A 1.0 uses supportedInterfaces, with url, protocolBinding and protocolVersion in each entry. The individual repair page shows an excerpt for that declared version.

JSON-RPC, HTTP+JSON and gRPC are different bindings. An MCP release date, OpenAPI version or the agent’s software version is not its A2A protocol version. Consult the 0.2 specification ↗, 0.3 specification ↗ or 1.0 specification ↗ for the complete card.

LocalMark checks up to three explicitly advertised supported interfaces, with bounded requests. It never guesses hidden paths. Authentication requirements, unsupported transports, temporary network failures and incomplete replies remain separate honest observations.

Do not remove required authentication just to obtain a badge. A protected or untested interface can remain in the all-agents directory without a confirmed public A2A response.