Struct ToolCall 

pub struct ToolCall {
    pub id: String,
    pub name: String,
    pub arguments: Value,
    pub reasoning_state: Option<ReasoningState>,
}

A request from the model to execute a tool.

This represents an “intent” to call a tool - the tool has NOT been executed. The consumer is responsible for:

1. Looking up the tool by name
2. Parsing and validating arguments
3. Executing the tool
4. Returning results to the model

Fields

id: String

Unique identifier for this tool call.

Used to correlate tool results with their requests when continuing the conversation.

name: String

Name of the tool to execute.

arguments: Value

Arguments to pass to the tool, as a JSON value.

The structure depends on the tool’s schema.

reasoning_state: Option<ReasoningState>

Provider reasoning state bound to this specific call.

Gemini attaches a thought signature to each function call rather than to the turn, so it lives here; providers that scope reasoning to the whole turn use Message::assistant_with_reasoning instead.

Implementations

impl ToolCall

pub fn new( id: impl Into<String>, name: impl Into<String>, arguments: Value, ) -> Self

Creates a new tool call.

pub fn with_reasoning_state(self, state: ReasoningState) -> Self

Binds provider reasoning state to this call.

Used by providers that sign each function call individually, so the signature travels with the call it belongs to instead of the turn.

pub fn arguments_json(&self) -> String

Returns the arguments as a JSON string.

Trait Implementations

impl Clone for ToolCall

fn clone(&self) -> ToolCall

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ToolCall

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ToolCall

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for ToolCall

impl PartialEq for ToolCall

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for ToolCall

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ToolCall