Enum MessageContent 

pub enum MessageContent {
    Text {
        text: String,
    },
    Thinking {
        text: String,
        signature: Option<String>,
    },
    ToolUse {
        id: String,
        name: String,
        args: Value,
    },
    ToolResult {
        tool_use_id: String,
        output: ToolResultBody,
        is_error: bool,
    },
    Image {
        mime: String,
        data: ImageData,
    },
    ProviderActivity {
        provider_id: String,
        kind: ProviderActivityKind,
        payload: Value,
    },
}

A piece of content inside a message body.

Both “the model requesting a tool call in the previous turn” and “the tool result reported back in the current turn” are placed in the messages array, matching the shape of the Anthropic Messages API. OpenAI uses separate assistant message with tool_calls + tool message; the codec translates between the two during encoding.

Variants

Text

Fields

text: String

Thinking

The thinking chain produced by the model in the previous turn. Only present in Role::Assistant messages.

signature is the anti-forgery signature for Anthropic extended thinking: it must be kept together with the text. For providers that echo plain text (e.g. DeepSeek-v4-pro), this is None.

Fields

text: String

signature: Option<String>

ToolUse

Tool call from a previous turn: when sending a request, include both the prior tool_use and tool_result in messages so the provider can reconstruct the context.

Fields

id: String

name: String

args: Value

ToolResult

Fields

tool_use_id: String

output: ToolResultBody

is_error: bool

Image

Multimodal input. (P2)

Fields

mime: String

data: ImageData

ProviderActivity

Provider-hosted capability activity (e.g. hosted web_search, hosted code execution). The agent does not interpret payload; it passes it through when retrying the same provider, or the codec decides how to degrade when switching providers.

payload uses #[serde(skip)]: it is dropped when persisting across processes; on session resume, if the model re-triggers the same hosted call, a new hosted call is made without relying on the old payload.

Fields

provider_id: String

kind: ProviderActivityKind

payload: Value

Trait Implementations

impl Clone for MessageContent

fn clone(&self) -> MessageContent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MessageContent

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for MessageContent

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for MessageContent

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for MessageContent

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 MessageContent