Enum Part 

pub enum Part {
    Thinking {
        thinking: String,
        signature: Option<String>,
    },
    Text {
        text: String,
    },
    InlineData {
        mime_type: String,
        data: Vec<u8>,
        uri: Option<String>,
        annotations: Option<Value>,
    },
    FileData {
        mime_type: String,
        file_uri: String,
        annotations: Option<Value>,
    },
    FunctionCall {
        name: String,
        args: Value,
        id: Option<String>,
        thought_signature: Option<String>,
    },
    FunctionResponse {
        function_response: FunctionResponseData,
        id: Option<String>,
        annotations: Option<Value>,
    },
    ServerToolCall {
        server_tool_call: Value,
    },
    ServerToolResponse {
        server_tool_response: Value,
    },
    EmbeddedResource {
        resource: EmbeddedResource,
    },
}

A single part of a Content message.

Parts can be text, binary data, file references, function calls/responses, thinking traces, or server-side tool interactions.

Variants

Thinking

Thinking/reasoning trace from a thinking-capable model.

Must be placed before Text in the enum so that #[serde(untagged)] deserialization matches {"thinking": "..."} before falling through to Text.

Fields

thinking: String

The reasoning/thinking text.

signature: Option<String>

Optional cryptographic signature for thought verification.

Text

Plain text content.

Fields

text: String

The text content.

InlineData

Inline binary data (images, audio, etc.).

Fields

mime_type: String

MIME type of the data.

data: Vec<u8>

Raw binary data.

uri: Option<String>

Optional source URI associated with the inline payload.

annotations: Option<Value>

Optional protocol or presentation annotations.

FileData

File data referenced by URI (URL or cloud storage path).

This allows referencing external files without embedding the data inline. Providers that don’t support URI-based content can fetch and convert to InlineData.

Example

use adk_core::Part;

let image_url = Part::FileData {
    mime_type: "image/jpeg".to_string(),
    file_uri: "https://example.com/image.jpg".to_string(),
    annotations: None,
};

Fields

mime_type: String

MIME type of the file (e.g., “image/jpeg”, “audio/wav”)

file_uri: String

URI to the file (URL, gs://, etc.)

annotations: Option<Value>

Optional protocol or presentation annotations.

FunctionCall

A function (tool) call from the model.

Fields

name: String

Name of the function to call.

args: Value

Arguments as a JSON value.

id: Option<String>

Tool call ID for OpenAI-style providers. None for Gemini.

thought_signature: Option<String>

Thought signature for Gemini 3 series models. Must be preserved and relayed back in conversation history during multi-turn function calling.

FunctionResponse

A function (tool) response.

Fields

function_response: FunctionResponseData

The function response data.

id: Option<String>

Tool call ID for OpenAI-style providers. None for Gemini.

annotations: Option<Value>

Optional protocol or presentation annotations.

ServerToolCall

Server-side tool call data from Gemini 3 built-in tool invocations. Stored as opaque JSON to avoid coupling core types to provider-specific schemas.

Fields

server_tool_call: Value

Opaque JSON payload for the server tool call.

ServerToolResponse

Server-side tool response data from Gemini 3 built-in tool invocations. Stored as opaque JSON to avoid coupling core types to provider-specific schemas.

Fields

server_tool_response: Value

Opaque JSON payload for the server tool response.

EmbeddedResource

A complete resource embedded in a message: a source URI plus inline text or binary contents. Mirrors the MCP / ACP embedded-resource block.

The resource key is unique among all Part variants, so untagged deserialization matches this variant unambiguously. This variant is additive: Content values serialized before it existed deserialize unchanged.

Example

use adk_core::{EmbeddedResource, Part, TextResourceContents};

let part = Part::EmbeddedResource {
    resource: EmbeddedResource::Text(TextResourceContents::new(
        "file:///main.rs",
        Some("text/x-rust".to_string()),
        "fn main() {}",
    )),
};
assert_eq!(part.embedded_resource().map(EmbeddedResource::uri), Some("file:///main.rs"));

Fields

resource: EmbeddedResource

The embedded resource (text or binary contents).

Implementations

impl Part

pub fn text(&self) -> Option<&str>

Returns the text content if this is a Text part, None otherwise

pub fn is_thinking(&self) -> bool

Returns true if this part is a Thinking variant

pub fn thinking_text(&self) -> Option<&str>

Returns the thinking text content if this is a Thinking part, None otherwise

pub fn mime_type(&self) -> Option<&str>

Returns the MIME type if this part has one (InlineData or FileData)

pub fn file_uri(&self) -> Option<&str>

Returns the file URI if this is a FileData part

pub fn uri(&self) -> Option<&str>

Returns the source URI for inline or referenced file data.

pub fn annotations(&self) -> Option<&Value>

Returns protocol or presentation annotations attached to this part.

pub fn is_media(&self) -> bool

Returns true if this part contains media (image, audio, video)

pub fn embedded_resource(&self) -> Option<&EmbeddedResource>

Returns the embedded resource if this is an EmbeddedResource part, None otherwise.

pub fn text_part(text: impl Into<String>) -> Part

Create a new text part

pub fn inline_data(mime_type: impl Into<String>, data: Vec<u8>) -> Part

Create a new inline data part

Panics

Panics if data exceeds MAX_INLINE_DATA_SIZE (10 MB).

pub fn file_data( mime_type: impl Into<String>, file_uri: impl Into<String>, ) -> Part

Create a new file data part from URI

Trait Implementations

impl Clone for Part

fn clone(&self) -> Part

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Part

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Part

fn deserialize<__D>( __deserializer: __D, ) -> Result<Part, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Part

fn eq(&self, other: &Part) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Part

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Part