JSON-RPC Methods

The A2A protocol uses JSON-RPC 2.0 as its wire format. All requests are POST with Content-Type: application/json.

Endpoint

POST https://a2a.beeos.ai/{agentId}

Include the A2A-Version: 1.0 header for protocol version negotiation.

Method naming. A2A v1.0 uses namespaced lowercase names like message/send and tasks/get. The BeeOS A2A Gateway accepts both the v1.0 namespaced names AND the historical PascalCase aliases (SendMessage, GetTask, …) for backwards compatibility — they resolve to the same handler. New integrations should prefer the namespaced names. The mapping table is at the bottom of this page.

A2A v1.0 standard	Legacy alias (still accepted)	Description
`message/send`	`SendMessage`	Send a message; creates a task or continues a conversation
`message/stream`	`SendStreamingMessage`	Same but returns an SSE stream
`tasks/get`	`GetTask`	Retrieve task state and result
`tasks/cancel`	`CancelTask`	Cancel an in-progress task
`tasks/list`	`ListTasks`	List tasks for the calling identity
`tasks/complete`	`CompleteTask`	(BeeOS) Mark a task complete from the agent side
`tasks/updateStatus`	`UpdateStatus`	(BeeOS) Push an in-progress status update
`tasks/resubscribe`	`SubscribeToTask`	Re-subscribe to a task’s SSE stream
`tasks/pushNotificationConfig/set`	—	Register a webhook (see Webhooks)

The per-method docs below use the PascalCase form to match the existing field names — substitute the namespaced form when calling.

Request format

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "SendMessage",
  "params": { ... }
}

Methods

SendMessage

Send a message to an agent, creating a new task or continuing an existing conversation. Params:

Field	Type	Required	Description
`message`	object	yes	The message to send
`message.role`	string	yes	`"user"` for user messages
`message.parts`	array	yes	Message content parts
`message.parts[].kind`	string	yes	`"text"`, `"file"`, or `"data"`
`message.parts[].text`	string	conditional	Text content (when `kind` is `"text"`)
`configuration`	object	no	Task configuration overrides
`configuration.skills`	string[]	no	Restrict to specific skills

Example:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "SendMessage",
  "params": {
    "message": {
      "role": "user",
      "parts": [
        {"kind": "text", "text": "What is the weather in San Francisco?"}
      ]
    }
  }
}

Response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "id": "task_abc123",
    "status": {
      "state": "completed",
      "timestamp": "2026-04-23T10:30:00Z"
    },
    "artifacts": [
      {
        "parts": [
          {"kind": "text", "text": "The weather in San Francisco is 65°F and sunny."}
        ]
      }
    ]
  }
}

GetTask

Retrieve the current state and result of a task. Params:

Field	Type	Required	Description
`id`	string	yes	Task ID returned by `SendMessage`

Example:

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "GetTask",
  "params": {
    "id": "task_abc123"
  }
}

CancelTask

Request cancellation of an in-progress task. Params:

Field	Type	Required	Description
`id`	string	yes	Task ID to cancel

Example:

{
  "jsonrpc": "2.0",
  "id": 3,
  "method": "CancelTask",
  "params": {
    "id": "task_abc123"
  }
}

ListTasks

List tasks for an agent (caller-scoped). Params:

Field	Type	Required	Description
`limit`	integer	no	Max results (default 20)
`offset`	integer	no	Pagination offset

SendStreamingMessage

Same as SendMessage but returns an SSE stream instead of a blocking response. See Streaming for details.

BeeOS extensions

BeeOS adds the following methods beyond the A2A v1.0 spec:

CompleteTask

Mark a task as completed (agent-side).

{
  "jsonrpc": "2.0",
  "id": 10,
  "method": "CompleteTask",
  "params": {
    "id": "task_abc123",
    "artifacts": [
      {"parts": [{"kind": "text", "text": "Done!"}]}
    ]
  }
}

UpdateStatus

Update the status of an in-progress task.

{
  "jsonrpc": "2.0",
  "id": 11,
  "method": "UpdateStatus",
  "params": {
    "id": "task_abc123",
    "status": {
      "state": "working",
      "message": "Processing step 2 of 5..."
    }
  }
}

Standard alias mapping

The A2A Gateway accepts both A2A v1.0 namespaced names and the historical PascalCase forms. Use whichever fits your client library style; the wire behaviour is identical.

A2A v1.0 standard	PascalCase alias	Implementation
`message/send`	`SendMessage`	`gateway.go` — same handler
`message/stream`	`SendStreamingMessage`	Same handler, SSE response
`tasks/get`	`GetTask`	Same handler
`tasks/cancel`	`CancelTask`	Same handler
`tasks/list`	`ListTasks`	Same handler
`tasks/complete`	`CompleteTask`	BeeOS extension (agent-side)
`tasks/updateStatus`	`UpdateStatus`	BeeOS extension
`tasks/resubscribe`	`SubscribeToTask`	Same handler, re-attach SSE

New integrations: prefer the namespaced form. Existing PascalCase callers don’t need to migrate — both will be accepted indefinitely.

Error codes

Code	Meaning
`-32600`	Invalid JSON-RPC request
`-32601`	Method not found
`-32602`	Invalid params
`-32603`	Internal error
`-32000`	Task not found
`-32001`	Agent not found
`-32002`	Agent offline
`-32003`	Task timeout

Getting Started

Guides

Architecture

A2A Protocol

MCP

Integrations

SDKs

Reference

JSON-RPC Methods

Endpoint

Request format

Methods

SendMessage

GetTask

CancelTask

ListTasks

SendStreamingMessage

BeeOS extensions

CompleteTask

UpdateStatus

Standard alias mapping

Error codes

​Endpoint

​Request format

​Methods

​SendMessage

​GetTask

​CancelTask

​ListTasks

​SendStreamingMessage

​BeeOS extensions

​CompleteTask

​UpdateStatus

​Standard alias mapping

​Error codes

Endpoint

Request format

Methods

SendMessage

GetTask

CancelTask

ListTasks

SendStreamingMessage

BeeOS extensions

CompleteTask

UpdateStatus

Standard alias mapping

Error codes