curl --request POST \
  --url https://api.getsly.ai/v1/a2a/{agentId} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "jsonrpc": "2.0",
  "method": "message/send",
  "params": {},
  "id": "<string>"
}
'

{
  "jsonrpc": "2.0",
  "id": "<string>",
  "result": "<unknown>",
  "error": {
    "code": 123,
    "message": "<string>",
    "data": "<unknown>"
  }
}