Send message request

Send Message Request (Client)

1. Description

This hook is called when the observed client agent sends a message to server agent to initiate a new interaction or to continue an existing one through A2A protocol.
This hook must be used before the observed agent sends the A2A-compliant message to server agent.

2. Method

message/send

3. Reponse

The response is an AOSSuccessResponse object.

Decision	Behavior
allow	The observed agent should send the A2A-compliant to the target agent.
deny	The A2A-compliant message should be blocked and not sent to the target agent.
modify	The observed agent should send the A2A message with the modified content found in modifiedRequest field.

4. A2A payload

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "message/send",
  "params": {
    "message": {
      "role": "agent",
      "parts": [
        {
          "kind": "text",
          "text": "how to prepare a cheese cake?"
        }
      ],
      "messageId": "9229e770-767c-417b-a0b0-f0741243c589"
    },
    "metadata": {}
  }
}

5. AOS payload

{
     "jsonrpc": "2.0",
     "id": "03c5db45-6455-4081-897a-4225267113ce",
     "method": "message/send",
     "params": {
         "payload": {
             "jsonrpc": "2.0",
             "id": 1,
             "method": "message/send",
             "params": {
                 "message": {
                     "role": "agent",
                     "parts": [
                     {
                         "kind": "text",
                         "text": "how to prepare a cheese cake?"
                     }
                     ],
                     "messageId": "9229e770-767c-417b-a0b0-f0741243c589"
                 },
                 "metadata": {}
             }
         },
         "reasoning": "Best to complete the task is to delegate it to the agent that specializes in cakes.",
         "context": {
             "from": {
                 "agent": {
                     "name": "Cooking assistant",
                     "url": "https://cooking-assistant.openai.com/api/v1",
                     "instructions": "You are a helpful assistant that can answer questions and help with tasks related to cooking.",
                     "version": "1.0.0",
                     "provider": {
                         "name": "OpenAI",
                         "url": "https://openai.com"
                     }
                 },
                 "role": "client"
             },
             "to": {
                 "agent": {
                     "url": "https://api.cakebaker.com/v1",
                     "name": "Cake Baker",
                     "version": "1.0.0"
                 },
                 "role": "server"
             }
         }
     }
 }

Send Message Request (Server)

1. Description

This hook is called when the observed server agent received send message request.
This hook must be used before the observed agent processes the A2A-compliant message.

2. Method

message/send

3. Reponse

The response is an AOSSuccessResponse object.

Decision	Behavior
allow	The observed agent should process the A2A-compliant.
deny	The A2A-compliant message should be ignored and not processed by the server agent.
modify	The observed agent should process the A2A message with the modified content found in modifiedRequest field.

4. A2A payload

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "message/send",
  "params": {
    "message": {
      "role": "agent",
      "parts": [
        {
          "kind": "text",
          "text": "how to prepare a cheese cake?"
        }
      ],
      "messageId": "9229e770-767c-417b-a0b0-f0741243c589"
    },
    "metadata": {}
  }
}

5. AOS payload

{
     "jsonrpc": "2.0",
     "id": "03c5db45-6455-4081-897a-4225267113ce",
     "method": "message/send",
     "params": {
         "payload": {
             "jsonrpc": "2.0",
             "id": 1,
             "method": "message/send",
             "params": {
                 "message": {
                     "role": "agent",
                     "parts": [
                     {
                         "kind": "text",
                         "text": "how to prepare a cheese cake?"
                     }
                     ],
                     "messageId": "9229e770-767c-417b-a0b0-f0741243c589"
                 },
                 "metadata": {}
             }
         },
         "context": {
             "from": {
                 "agent": {
                     "url": "https://cooking-assistant.openai.com/api/v1",
                     "name": "Cooking assistant",
                     "version": "1.0.0"
                 },
                 "role": "client"
             },
             "to": {
                 "agent": {
                     "name": "Cake Bake",
                     "url": "https://api.cakebaker.com/v1",
                     "instructions": "You are a helpful assistant that specializies in answering questions and tasks related to cake baking.",
                     "version": "1.0.0",
                     "provider": {
                         "name": "AzureAIFoundry",
                         "url": "https://ai.azure.com"
                     }
                 },
                 "role": "server"
             }
         }
     }
 }