A2A mailbox

Trikstar has a public A2A mailbox where an AI agent can send a request on behalf of its user. Typical requests include an invoice, reminder, request, commercial offer, or inquiry. The machine channel is simpler for both parties than e-mail or a robotic phone call. The mailbox is currently a trial, and we want to find out how many agents will use it.

Address

Mailbox address: https://a2a.trikstar.cz/
Agent Card: trikstar.cz/.well-known/agent-card.json

What is A2A

A2A (Agent2Agent) is an open standard for communication between independent AI agents that may come from different vendors. An agent first reads an Agent Card: a short description of the other agent in JSON format, detailing its capabilities and the address where it receives messages. Then it sends a message and receives a task with an identifier and status. The agent can inquire about the task’s status at any later time. The mailbox uses A2A version 1.0 and also accepts the older version 0.3.

How to instruct your agent

If you use an AI agent that can call web services, such as Claude Code or another programming assistant, just tell it what to send. Provide the address of the mailbox and the link to Trikstar’s Agent Card; both are listed above. The agent will determine from the Agent Card how to send the message and will return a task identifier to you. Save this identifier; it can be used to check the status.

Example call

curl -sS https://a2a.trikstar.cz/ \
  -H 'Content-Type: application/json' \
  -H 'A2A-Version: 1.0' \
  -d '{"jsonrpc": "2.0", "id": 1, "method": "SendMessage",
       "params": {"message": {"messageId": "m-1", "role": "ROLE_USER",
         "parts": [{"text": "Hello, please find the October invoice attached."}]}}}'

{"jsonrpc": "2.0", "id": 1, "result": {"task": {"id": "3f0c…", "contextId": "3f0c…",
  "status": {"state": "TASK_STATE_SUBMITTED", "timestamp": "…"}}}}

curl -sS https://a2a.trikstar.cz/ \
  -H 'Content-Type: application/json' \
  -H 'A2A-Version: 1.0' \
  -d '{"jsonrpc": "2.0", "id": 2, "method": "GetTask", "params": {"id": "3f0c…"}}'

What happens to a request

After receiving the request, we store it and return the task in the status “submitted”. No automated system reads, executes, or forwards it. A person reads it. After processing, the status changes to “completed” or “rejected”. The mailbox does not respond automatically; to receive a response, provide contact information in the request. We delete requests after 90 days.

Rules

One request may be up to 2 MB in size.
Attachments: up to 5, in the formats PDF, plain text, CSV, Markdown, JSON, PNG, JPEG, and WebP.
We accept up to 20 requests per hour from one address.
We do not require request signatures (HTTP Message Signatures, Web Bot Auth). If an agent sends one, we will verify and record it.

Data processing

The data controller for the information received by the mailbox is Cybermindnet s.r.o., company ID (IČO) 07126042, Vícenice 24, 339 01 Klatovy. We store the IP address and network (ASN) from which the request was made, the User-Agent and other request headers, the text and attachments of the request, and the signature if the agent sends it. The data is used to process the request, to protect against misuse, and to evaluate the service’s operation. We delete everything after 90 days. Send inquiries about data processing to info@cybermindnet.eu.

No agent?

Your assistant will write an e-mail for you. Send it to shop@trikstar.cz.