Struct Usage 

pub struct Usage {
    pub prompt_tokens: u64,
    pub completion_tokens: u64,
    pub cached_read_tokens: u64,
    pub cache_write_tokens: u64,
    pub reasoning_tokens: Option<u64>,
}

Fields

prompt_tokens: u64

Cache-INCLUSIVE prompt count (OpenAI convention): fresh + cached_read + cache_write. Translators normalize to this at the boundary so fresh = prompt_tokens - cached_read - cache_write holds uniformly (billing and rate-limit math rely on it). Anthropic’s wire reports input_tokens cache-exclusive — both Anthropic translators add the cache classes in, and the Anthropic client surface subtracts them back.

completion_tokens: u64

cached_read_tokens: u64

Provider-side prompt-cache reads (tokens reused from KV cache)

cache_write_tokens: u64

Tokens written to the prompt cache this turn (Anthropic cache_creation, which bills above the plain input rate)

reasoning_tokens: Option<u64>

Reasoning/CoT tokens inside completion_tokens, when the provider reports them (OpenAI completion_tokens_details.reasoning_tokens, Responses output_tokens_details, Gemini thoughtsTokenCount).

Trait Implementations

impl Clone for Usage

fn clone(&self) -> Usage

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Usage

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

Formats the value using the given formatter.

impl Default for Usage

fn default() -> Usage

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Usage

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for Usage

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

where __S: Serializer,

Serialize this value into the given Serde serializer.