Third-party agent integration

Protocol standard

The integration must be based on the Google A2A protocol. For more information, see the A2A 0.2.5 specification.

Integration process

1. Configure AgentCard

For the response and an example for step 3, see AgentCard.

2. Call the agent

For the request parameters and an example for step 4, see Agent call request fields.
For the response and an example for step 6, see Agent call response fields.

Field descriptions

AgentCard

Field	Type	Required	Description
name	String	Yes	The agent name.
description	String	Yes	The agent description.
url	String	Yes	The base HTTPS URL of the agent service. When streaming is supported, the `/stream` path suffix is automatically appended.
version	String	Yes	The agent version.
protocolVersion	String	Yes	The A2A protocol version that the agent supports.
capabilities	AgentCapabilities	Yes	Specifies the optional A2A protocol features supported, such as streaming.
security	String[]	No	The security requirements for communicating with the agent. The apiKey security policy is supported. When configured, requests to the agent include the following header: `X-API-KEY: <value> // The value is configured in the console.`
defaultInputModes	String[]	Yes	The input media types that the agent accepts. Currently, "text/plain" is supported.
defaultOutputModes	String[]	Yes	The output media types that the agent generates. Currently, "text/plain" is supported.
skills	AgentSkill[]	Yes	A list of agent skills. At least one item is required.

AgentCapabilities

Field Name	Type	Required	Description
streaming	Boolean	No	Specifies whether Server-Sent Events (SSE) streaming is supported.
extensions	AgentExtension[]	No	A list of supported extensions.

AgentExtension

Field Name	Type	Required	Description
uri	String	Yes	The URI of the supported extension. The URI includes a description of the extension's capabilities.
params	Map<String, Object>	No	Configuration parameters.

AgentSkill

Field Name	Type	Required	Description
id	String	Yes	A unique skill identifier within the agent.
name	String	Yes	The skill name.
description	String	Yes	The skill description.
tags	String[]	Yes	Keywords for the skill.
examples	String[]	No	Usage examples for the skill.
inputModes	String[]	No	The accepted media types. If set, this overwrites `defaultInputModes`.
outputModes	String[]	No	The output media types. If set, this overwrites `defaultOutputModes`.

Example

{
  "name": "Super AI Assistant",
  "description": "Repeats user input, calculates the sum of two numbers, counts user sentences, triggers a flash, and provides coaching for basketball and football. A versatile assistant.",
  "protocolVersion": "0.2.5",
  "url": "https://example/a2a/demo/v1",
  "version": "1.0.0",
  "capabilities": {
    "streaming": true,
    "extensions": []
  },
  "security": [],
  "defaultInputModes": [
    "text/plain"
  ],
  "defaultOutputModes": [
    "text/plain"
  ],
  "skills": [
    {
      "id": "ai-repeat",
      "name": "AI Repeater",
      "description": "Repeats what the user says.",
      "tags": [
        "demo",
        "repeat"
      ],
      "examples": [
        "Example: Repeat what I said."
      ]
    },
    {
      "id": "ai-calculate",
      "name": "AI Calculator",
      "description": "Calculates the 'sum' of two numbers.",
      "tags": [
        "demo",
        "calculate"
      ],
      "examples": [
        "Example: What is 1 plus 2?"
      ]
    },
    {
      "id": "ai-count",
      "name": "AI Counter",
      "description": "Records and counts the number of sentences the user has said.",
      "tags": [
        "demo",
        "count"
      ],
      "examples": [
        "Example: Count how many sentences I have said."
      ]
    },
    {
      "id": "ai-flash",
      "name": "AI Flash",
      "description": "Can perform a flash.",
      "tags": [
        "demo",
        "flash"
      ],
      "examples": [
        "Example: Perform a flash."
      ]
    },
    {
      "id": "ai-coach",
      "name": "AI Coach",
      "description": "Can teach you how to play basketball and football.",
      "tags": [
        "demo",
        "coach"
      ],
      "examples": [
        "Example: How to play basketball well."
      ]
    }
  ]
}

Agent call request fields

Field Name	Type	Required	Description
jsonrpc	String	Yes	Fixed value: "2.0".
method	String	Yes	`"message/stream"`: For requests that support SSE streaming. `"message/send"` does not support SSE streaming requests.
params	MessageSendParams	Yes	Request parameters.
id	String	Yes	The request ID.

MessageSendParams

Field Name	Type	Required	Description
message	Message	Yes	The content of the message to send.

Message

Field Name	Type	Required	Description
kind	String	Yes	Fixed value: "message".
role	String	Yes	"user": The message is sent by the user. "agent": The message is returned by the agent.
parts	Part[]	Yes	An array of content parts. It must contain at least one part.
messageId	String	Yes	The message identifier generated by the message sender.
contextId	String	No	The context identifier associated with the message.
metadata	Map<String, Object>	No	Metadata associated with this message.

Part

Field name	Type	Required	Description
kind	String	Yes	Identifies the content type of this part. For example, 'text' indicates a text type.
text	String	No	The text content of the part. Fill this in when kind=text.

Examples

HTTP request

{
  "jsonrpc": "2.0",
  "id": "request-1",
  "method": "message/send",
  "params": {
    "message": {
      "messageId": "msg-1",
      "kind": "message",
      "role": "user",
      "parts": [
        {
          "kind": "text",
          "text": "Will it rain today?"
        }
      ]
    }
  }
}

HTTP SSE request

{
  "jsonrpc": "2.0",
  "id": "request-1",
  "method": "message/stream",
  "params": {
    "message": {
      "messageId": "msg-1",
      "kind": "message",
      "role": "user",
      "parts": [
        {
          "kind": "text",
          "text": "Will it rain today?"
        }
      ]
    }
  }
}

Agent call response fields

Field Name	Type	Required	Description
jsonrpc	String	Yes	Fixed value: "2.0".
id	String	Yes	The request ID. It is the same as the value of `JSONRPCRequest.id`.
result	Task \| TaskStatusUpdateEvent \| TaskArtifactUpdateEvent	No	Returned when the request is processed successfully.
error	JSONRpcError	No	Returned when the request fails to be processed.

Task

Field Name	Type	Required	Description
id	String	Yes	A unique task identifier generated by the server, such as a UUID.
contextId	String	Yes	A server-generated ID for context alignment across multiple interaction turns.
status	TaskStatus	Yes	The current status of the task.
artifacts	Artifact[]	No	The output generated by the agent in this task.

TaskStatus

Field name	Type	Required	Description
state	String	Yes	The current lifecycle state of the task: submitted: The agent has received and confirmed the task, but processing has not started. working: The agent is processing the task. The client can expect further updates or a final state. completed: The task is successfully completed. failed: An error occurred during processing. input-required: The agent requires additional input from the user to continue. The multimodal interaction service will then pass the user's next input to this agent. rejected: The task is terminated. The multimodal interaction service will then take over the processing of the current request.
timestamp	String	No	The timestamp when this status was recorded. UTC time is recommended.

Field name

Type

Required

Description

state

String

Yes

The current lifecycle state of the task:

submitted: The agent has received and confirmed the task, but processing has not started.
working: The agent is processing the task. The client can expect further updates or a final state.
completed: The task is successfully completed.
failed: An error occurred during processing.
input-required: The agent requires additional input from the user to continue. The multimodal interaction service will then pass the user's next input to this agent.
rejected: The task is terminated. The multimodal interaction service will then take over the processing of the current request.

timestamp

String

The timestamp when this status was recorded. UTC time is recommended.

Artifact

Field Name	Type	Required	Description
artifactId	String	Yes	The identifier for the result generated by the agent.
parts	Part[]	Yes	The content of the result. It must contain at least one part.
metadata	Map<String, Object>	No	Metadata associated with this message.

TaskStatusUpdateEvent

Field Name	Type	Required	Description
taskId	String	Yes	The ID of the task being updated.
contextId	String	Yes	The context ID of the associated task.
kind	String	Yes	Fixed value: status-update.
status	TaskStatus	Yes	The new TaskStatus state.
final	Boolean	No	If true, this is the final status update for the current stream loop. The server usually closes the SSE connection afterward.

TaskArtifactUpdateEvent

Field Name	Type	Required	Description
taskId	String	Yes	The task ID associated with the generated result part.
contextId	String	Yes	The context ID of the associated task.
kind	String	Yes	Fixed value: artifact-update.
artifact	Artifact	Yes	The result data. It can be a complete result or an incremental result.
append	Boolean	No	If true, this part is appended to the returned result. If false (default), it replaces the returned result.
lastChunk	Boolean	No	If true, this is the final update for this result.

JSONRpcError

Field name	Type	Required	Description
code	Integer	Yes	The error code.
message	String	Yes	A description of the error.

Examples

HTTP response

{
  "id": "request-1",
  "jsonrpc": "2.0",
  "result": {
    "id": "task-1",
    "contextId": "context-1",
    "kind": "task",
    "status": {
      "state": "completed",
      "timestamp": "2025-07-15T14:50:28.575338Z"
    },
    "artifacts": [
      {
        "artifactId": "c3fee4d5-7234-48a1-8d2c-cfb715c5ce9e",
        "parts": [
          {
            "kind": "text",
            "text": "The weather is sunny today, "
          }
        ]
      },
      {
        "artifactId": "c3fee4d5-7234-48a1-8d2c-cfb715c5ce9e",
        "parts": [
          {
            "kind": "text",
            "text": "no rain."
          }
        ]
      }
    ]
  }
}

HTTP SSE response

{
  "id": "request-1",
  "jsonrpc": "2.0",
  "result": {
    "id": "task-1",
    "contextId": "context-1",
    "kind": "task",
    "status": {
      "state": "submitted",
      "timestamp": "2025-07-15T14:52:28.277547Z"
    }
  }
}

{
  "id": "request-1",
  "jsonrpc": "2.0",
  "result": {
    "taskId": "task-1",
    "contextId": "context-1",
    "kind": "artifact-update",
    "artifact": {
      "artifactId": "82eb84b9-0d73-4072-95f8-03655adfbf25",
      "parts": [
        {
          "kind": "text",
          "text": "The weather is sunny today, "
        }
      ]
    },
    "append": true,
    "lastChunk": false
  }
}

{
  "id": "request-1",
  "jsonrpc": "2.0",
  "result": {
    "taskId": "task-1",
    "contextId": "context-1",
    "kind": "artifact-update",
    "artifact": {
      "artifactId": "82eb84b9-0d73-4072-95f8-03655adfbf25",
      "parts": [
        {
          "kind": "text",
          "text": "no rain."
        }
      ]
    },
    "append": true,
    "lastChunk": true
  }
}

{
  "id": "request-1",
  "jsonrpc": "2.0",
  "result": {
    "taskId": "task-1",
    "contextId": "context-1",
    "kind": "status-update",
    "status": {
      "state": "completed",
      "timestamp": "2025-07-15T14:52:28.277643Z"
    },
    "final": true
  }
}

Integration example

To test the integration process for a self-developed agent, enter https://example/.well-known/agent.json in the console:

Further integration

You have now completed the basic integration of your self-developed agent with the multimodal interaction suite. For further integration, see the following topics:

​Protocol standard

​Integration process

​1. Configure AgentCard

​2. Call the agent

​Field descriptions

​AgentCard

​AgentCapabilities

​AgentExtension

​AgentSkill

​Example

​Agent call request fields

​MessageSendParams

​Message

​Part

​Examples

HTTP request

HTTP SSE request

​Agent call response fields

​Task

​TaskStatus

​Artifact

​TaskStatusUpdateEvent

​TaskArtifactUpdateEvent

​JSONRpcError

​Examples

HTTP response

HTTP SSE response

​Integration example

​Further integration

Protocol standard

Integration process

1. Configure AgentCard

2. Call the agent

Field descriptions

AgentCard

AgentCapabilities

AgentExtension

AgentSkill

Example

Agent call request fields

MessageSendParams

Message

Part

Examples

Agent call response fields

Task

TaskStatus

Artifact

TaskStatusUpdateEvent

TaskArtifactUpdateEvent

JSONRpcError

Examples

Integration example

Further integration