Enum ToolChoice 

pub enum ToolChoice {
    Auto,
    None,
    Any,
    Specific(SpecificToolChoice),
}

Tool choice configuration that works across different providers Based on OpenAI, Anthropic, and Gemini API specifications Follows Anthropic’s tool use best practices for optimal performance

Variants

Auto

Let the model decide whether to call tools (“auto”) Default behavior - allows model to use tools when appropriate

None

Force the model to not call any tools (“none”) Useful for pure conversational responses without tool usage

Any

Force the model to call at least one tool (“any”) Ensures tool usage even when model might prefer direct response

Specific(SpecificToolChoice)

Force the model to call a specific tool Useful for directing model to use particular functionality

Implementations

impl ToolChoice

pub fn auto() -> Self

Create auto tool choice (default behavior)

pub fn none() -> Self

Create none tool choice (disable tool calling)

pub fn any() -> Self

Create any tool choice (force at least one tool call)

pub fn function(name: String) -> Self

Create specific function tool choice

pub fn allows_parallel_tools(&self) -> bool

Check if this tool choice allows parallel tool use Based on Anthropic’s parallel tool use guidelines

pub fn description(&self) -> &'static str

Get human-readable description of tool choice behavior

pub fn to_provider_format(&self, provider: &str) -> Value

Convert to provider-specific format

Trait Implementations

impl Clone for ToolChoice

fn clone(&self) -> ToolChoice

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ToolChoice

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ToolChoice

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ToolChoice

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

where __S: Serializer,

Serialize this value into the given Serde serializer.