Tasks API

Tasks represent ongoing conversations or operations between agents. See the A2A Task spec for the full protocol definition.

Task States

State	Description
submitted	Task received, pending processing. If the recipient is offline, the message is queued and the task stays in this state until delivery.
working	Agent is processing
input-required	Waiting for user input
completed	Successfully completed
failed	Error occurred, or queue TTL expired
canceled	Canceled by user (also purges any queued messages for this task)
rejected	Rejected by agent

Get Task

POST /a2a
A2A-Version: 1.0
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "method": "GetTask",
  "params": {
    "id": "task-123",
    "historyLength": 10
  },
  "id": 1
}

Response:

{
  "jsonrpc": "2.0",
  "result": {
    "id": "task-123",
    "contextId": "ctx-456",
    "status": {
      "state": "completed",
      "timestamp": "2026-02-28T12:00:00Z"
    },
    "messages": [...],
    "artifacts": [...]
  },
  "id": 1
}

Cancel Task

POST /a2a
A2A-Version: 1.0
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "method": "CancelTask",
  "params": {
    "id": "task-123"
  },
  "id": 1
}

Artifacts

Tasks can produce artifacts (files, data):

{
  "artifacts": [
    {
      "id": "artifact-1",
      "name": "report.pdf",
      "mimeType": "application/pdf",
      "parts": [
        {"kind": "file", "data": "base64..."}
      ]
    }
  ]
}