Tasks API

Tasks represent ongoing conversations or operations between agents.

Task States

State	Description
submitted	Task received, pending processing
working	Agent is processing
input-required	Waiting for user input
completed	Successfully completed
failed	Error occurred
canceled	Canceled by user
rejected	Rejected by agent

Get Task

POST /a2a
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "method": "tasks/get",
  "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
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "method": "tasks/cancel",
  "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..."}
      ]
    }
  ]
}