Step

A step in the interaction.

Fields
type Union type
The following is a list of mutually exclusive fields. At most one of the fields will be set in a response:
thought object (ThoughtStep)
toolCall object (ToolCallStep)
toolResult object (ToolResultStep)
userInput object (UserInputStep)

DO NOT USE -- These are for 3P JSON only

modelOutput object (ModelOutputStep)
text
(deprecated) object (LegacyTextContent)
image
(deprecated) object (LegacyImageContent)
audio
(deprecated) object (LegacyAudioContent)
document
(deprecated) object (LegacyDocumentContent)
video
(deprecated) object (LegacyVideoContent)
End of mutually exclusive fields.
JSON representation 
{

  // type
  "thought": {
    object (ThoughtStep)
  },
  "toolCall": {
    object (ToolCallStep)
  },
  "toolResult": {
    object (ToolResultStep)
  },
  "userInput": {
    object (UserInputStep)
  },
  "modelOutput": {
    object (ModelOutputStep)
  },
  "text": {
    object (LegacyTextContent)
  },
  "image": {
    object (LegacyImageContent)
  },
  "audio": {
    object (LegacyAudioContent)
  },
  "document": {
    object (LegacyDocumentContent)
  },
  "video": {
    object (LegacyVideoContent)
  }
  // Union type
}

ThoughtStep

A thought step.

Fields
signature string (bytes format)

A signature hash for backend validation.

A base64-encoded string.

summary[] object (Content)

A summary of the thought.

JSON representation 
{
  "signature": string,
  "summary": [
    {
      object (Content)
    }
  ]
}

ToolCallStep

Tool call step.

Fields
id string

Required. A unique id for this specific tool call.

signature string (bytes format)

A signature hash for backend validation.

A base64-encoded string.

type Union type
The following is a list of mutually exclusive fields. At most one of the fields will be set in a response:
functionCall object (FunctionCallStep)
codeExecutionCall object (CodeExecutionCallStep)
urlContextCall object (UrlContextCallStep)
mcpServerToolCall object (McpServerToolCallStep)
googleSearchCall object (GoogleSearchCallStep)
fileSearchCall object (FileSearchCallStep)
googleMapsCall object (GoogleMapsCallStep)
retrievalCall object (RetrievalCallStep)
End of mutually exclusive fields.
JSON representation 
{
  "id": string,
  "signature": string,

  // type
  "functionCall": {
    object (FunctionCallStep)
  },
  "codeExecutionCall": {
    object (CodeExecutionCallStep)
  },
  "urlContextCall": {
    object (UrlContextCallStep)
  },
  "mcpServerToolCall": {
    object (McpServerToolCallStep)
  },
  "googleSearchCall": {
    object (GoogleSearchCallStep)
  },
  "fileSearchCall": {
    object (FileSearchCallStep)
  },
  "googleMapsCall": {
    object (GoogleMapsCallStep)
  },
  "retrievalCall": {
    object (RetrievalCallStep)
  }
  // Union type
}

FunctionCallStep

A function tool call step.

Fields
name string

Required. The name of the tool to call.

arguments object (Struct)

Required. The arguments to pass to the function.

JSON representation 
{
  "name": string,
  "arguments": {
    object (Struct)
  }
}

CodeExecutionCallStep

code execution call step.

Fields
arguments object (CodeExecutionCallStepArguments)

Required. The arguments to pass to the code execution.

JSON representation 
{
  "arguments": {
    object (CodeExecutionCallStepArguments)
  }
}

CodeExecutionCallStepArguments

The arguments to pass to the code execution.

Fields
language enum (Language)

Programming language of the code.

code string

The code to be executed.

JSON representation 
{
  "language": enum (Language),
  "code": string
}

Language

Supported programming languages for the generated code.

Enums
LANGUAGE_UNSPECIFIED Unspecified language. This value should not be used.
PYTHON Python >= 3.10, with numpy and simpy available.

UrlContextCallStep

URL context call step.

Fields
arguments object (UrlContextCallStepArguments)

Required. The arguments to pass to the URL context.

JSON representation 
{
  "arguments": {
    object (UrlContextCallStepArguments)
  }
}

UrlContextCallStepArguments

The arguments to pass to the URL context.

Fields
urls[] string

The URLs to fetch.

JSON representation 
{
  "urls": [
    string
  ]
}

McpServerToolCallStep

MCPServer tool call step.

Fields
name string

Required. The name of the tool which was called.

serverName string

Required. The name of the used MCP server.

arguments object (Struct)

Required. The JSON object of arguments for the function.

JSON representation 
{
  "name": string,
  "serverName": string,
  "arguments": {
    object (Struct)
  }
}

GoogleSearchCallStep

Google Search call step.

Fields
arguments object (GoogleSearchCallStepArguments)

Required. The arguments to pass to Google Search.

searchType enum (SearchType)

The type of search grounding enabled.

JSON representation 
{
  "arguments": {
    object (GoogleSearchCallStepArguments)
  },
  "searchType": enum (SearchType)
}

GoogleSearchCallStepArguments

The arguments to pass to Google Search.

Fields
queries[] string

Web search queries for the following-up web search.

JSON representation 
{
  "queries": [
    string
  ]
}

FileSearchCallStep

This type has no fields.

File Search call step.

GoogleMapsCallStep

Google Maps call step.

Fields
arguments object (GoogleMapsCallStepArguments)

The arguments to pass to the Google Maps tool.

JSON representation 
{
  "arguments": {
    object (GoogleMapsCallStepArguments)
  }
}

GoogleMapsCallStepArguments

The arguments to pass to the Google Maps tool.

Fields
queries[] string

The queries to be executed.

JSON representation 
{
  "queries": [
    string
  ]
}

RetrievalCallStep

Retrieval call step. Used by Vertex Retrieval tools such as Parallel AI, Exa AI, Agent Platform Search, etc. RetrievalType decides which tool is used.

Fields
arguments object (RetrievalStepArguments)

Required. The arguments to pass to the retrieval tool.

retrievalType enum (RetrievalType)

The type of retrieval tools.

JSON representation 
{
  "arguments": {
    object (RetrievalStepArguments)
  },
  "retrievalType": enum (RetrievalType)
}

ToolResultStep

Tool result step.

Fields
callId string

Required. id to match the id from the function call block.

signature string (bytes format)

A signature hash for backend validation.

A base64-encoded string.

type Union type
The following is a list of mutually exclusive fields. At most one of the fields will be set in a response:
functionResult object (FunctionResultStep)
codeExecutionResult object (CodeExecutionResultStep)
urlContextResult object (UrlContextResultStep)
googleSearchResult object (GoogleSearchResultStep)
mcpServerToolResult object (McpServerToolResultStep)
fileSearchResult object (FileSearchResultStep)
googleMapsResult object (GoogleMapsResultStep)
retrievalResult object (RetrievalResultStep)
End of mutually exclusive fields.
JSON representation 
{
  "callId": string,
  "signature": string,

  // type
  "functionResult": {
    object (FunctionResultStep)
  },
  "codeExecutionResult": {
    object (CodeExecutionResultStep)
  },
  "urlContextResult": {
    object (UrlContextResultStep)
  },
  "googleSearchResult": {
    object (GoogleSearchResultStep)
  },
  "mcpServerToolResult": {
    object (McpServerToolResultStep)
  },
  "fileSearchResult": {
    object (FileSearchResultStep)
  },
  "googleMapsResult": {
    object (GoogleMapsResultStep)
  },
  "retrievalResult": {
    object (RetrievalResultStep)
  }
  // Union type
}

FunctionResultStep

result of a function tool call.

Fields
name string

The name of the tool that was called.

isError boolean

Whether the tool call resulted in an error.

result object (Value)

Required. The result of the tool call.

JSON representation 
{
  "name": string,
  "isError": boolean,
  "result": {
    object (Value)
  }
}

CodeExecutionResultStep

code execution result step.

Fields
result string

Required. The output of the code execution.

isError boolean

Whether the code execution resulted in an error.

JSON representation 
{
  "result": string,
  "isError": boolean
}

UrlContextResultStep

URL context result step.

Fields
result[] object (UrlContextResultItem)

Required. The results of the URL context.

isError boolean

Whether the URL context resulted in an error.

JSON representation 
{
  "result": [
    {
      object (UrlContextResultItem)
    }
  ],
  "isError": boolean
}

UrlContextResultItem

The result of the URL context.

Fields
url string

The URL that was fetched.

status enum (Status)

The status of the URL retrieval.

JSON representation 
{
  "url": string,
  "status": enum (Status)
}

Status

The status of the URL retrieval.

Enums
STATUS_UNSPECIFIED
SUCCESS
ERROR
PAYWALL
UNSAFE

GoogleSearchResultStep

Google Search result step.

Fields
result[] object (GoogleSearchResultItem)

Required. The results of the Google Search.

isError boolean

Whether the Google Search resulted in an error.

JSON representation 
{
  "result": [
    {
      object (GoogleSearchResultItem)
    }
  ],
  "isError": boolean
}

GoogleSearchResultItem

The result of the Google Search.

Fields
searchSuggestions string

Web content snippet that can be embedded in a web page or an app webview.

JSON representation 
{
  "searchSuggestions": string
}

McpServerToolResultStep

MCPServer tool result step.

Fields
name string

name of the tool which is called for this specific tool call.

serverName string

The name of the used MCP server.

result object (Value)

Required. The output from the MCP server call. Can be simple text or rich content.

JSON representation 
{
  "name": string,
  "serverName": string,
  "result": {
    object (Value)
  }
}

FileSearchResultStep

This type has no fields.

File Search result step.

GoogleMapsResultStep

Google Maps result step.

Fields
result[] object (GoogleMapsResultItem)
JSON representation 
{
  "result": [
    {
      object (GoogleMapsResultItem)
    }
  ]
}

GoogleMapsResultItem

The result of the Google Maps.

Fields
places[] object (GoogleMapsResultPlaces)
widgetContextToken string
JSON representation 
{
  "places": [
    {
      object (GoogleMapsResultPlaces)
    }
  ],
  "widgetContextToken": string
}

GoogleMapsResultPlaces

Fields
placeId string
name string
url string
reviewSnippets[] object (ReviewSnippet)
JSON representation 
{
  "placeId": string,
  "name": string,
  "url": string,
  "reviewSnippets": [
    {
      object (ReviewSnippet)
    }
  ]
}

RetrievalResultStep

Vertex Retrieval result step. Used by Vertex Retrieval tools such as Parallel AI, Exa AI, Agent Platform Search, etc.

Fields
isError boolean

Whether the retrieval resulted in an error.

JSON representation 
{
  "isError": boolean
}

UserInputStep

Input provided by the user.

Fields
content Union type
The following is a list of mutually exclusive fields. At most one of the fields will be set in a response:
contentList object (ContentList)

The content of the step. An array of Content objects.

contentString string

The content of the step. A single string.

End of mutually exclusive fields.
JSON representation 
{

  // content
  "contentList": {
    object (ContentList)
  },
  "contentString": string
  // Union type
}

ModelOutputStep

Output generated by the model.

Fields
content[] object (Content)
error
(deprecated) object (Status)

The error result of the operation in case of failure or cancellation.

JSON representation 
{
  "content": [
    {
      object (Content)
    }
  ],
  "error": {
    object (Status)
  }
}