Struct CountTokensRequest 

#[non_exhaustive]
pub struct CountTokensRequest {
    pub model: ModelId,
    pub messages: Vec<MessageInput>,
    pub system: Option<SystemPrompt>,
    pub tools: Vec<Tool>,
    pub tool_choice: Option<ToolChoice>,
    pub thinking: Option<ThinkingConfig>,
    pub mcp_servers: Vec<McpServerConfig>,
}

Request payload for POST /v1/messages/count_tokens.

Construct via CountTokensRequest::builder.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

model: ModelId

Model whose tokenizer to use.

messages: Vec<MessageInput>

Conversation history.

system: Option<SystemPrompt>

Optional system prompt.

tools: Vec<Tool>

Tools that would be exposed.

tool_choice: Option<ToolChoice>

Tool-use policy.

thinking: Option<ThinkingConfig>

Extended-thinking configuration.

mcp_servers: Vec<McpServerConfig>

MCP servers exposed.

Implementations

impl CountTokensRequest

pub fn builder() -> CountTokensRequestBuilder

Begin configuring a token-count request.

Trait Implementations

impl Clone for CountTokensRequest

fn clone(&self) -> CountTokensRequest

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CountTokensRequest

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

Formats the value using the given formatter.

impl From<&CreateMessageRequest> for CountTokensRequest

fn from(req: &CreateMessageRequest) -> Self

Project a CreateMessageRequest onto the subset of fields the count-tokens endpoint accepts. Sampling parameters (temperature, top_p, etc.) and max_tokens are dropped because they don’t affect tokenization.

impl Serialize for CountTokensRequest

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

where __S: Serializer,

Serialize this value into the given Serde serializer.