> ## Documentation Index > Fetch the complete documentation index at: https://docs.niadra.com/llms.txt > Use this file to discover all available pages before exploring further. # Agents' prompt cache > Tokens, the provider's cache hit rate and the estimated savings, per agent, vendor or model. ## OpenAPI ````yaml openapi/en/cell.json GET /v1/usage/prompt-cache openapi: 3.1.0 info: title: Niadra data API version: '1' description: >- Writing, context, history, objects, identity, privacy and governance of one space. Every space has a stable address, with the space and the region in its name. servers: - url: https://{space}.{region}.api.niadra.com variables: space: default: acme-prod description: The space, which comes in the source key. region: default: us-east-2 description: The region of the space, which also comes in the key. security: [] paths: /v1/usage/prompt-cache: get: tags: - usage summary: Agents' prompt cache description: >- The agents' prompt cache: tokens, cache hits and the estimated saving, from the usage the SDK read from each model call. **Authentication.** Console person token with the `analysis`, `vendor` role (or admin), or a source key with the `admin` scope. operationId: prompt_cache_v1_usage_prompt_cache_get parameters: - in: query name: since required: false schema: anyOf: - format: date type: string - type: 'null' title: Since - in: query name: until required: false schema: anyOf: - format: date type: string - type: 'null' title: Until - in: query name: group_by required: false schema: anyOf: - items: type: string type: array - type: 'null' title: Group By - in: query name: source_id required: false schema: anyOf: - format: uuid type: string - type: 'null' title: Source Id responses: '200': content: application/json: schema: $ref: '#/components/schemas/PromptCacheReport' description: Successful Response '422': content: application/problem+json: schema: $ref: '#/components/schemas/Problem' description: The request does not match the contract. security: - sourceKey: [] - personToken: [] components: schemas: PromptCacheReport: additionalProperties: false description: >- `GET /v1/usage/prompt-cache`: the agents' prompt cache, from what the providers reported. properties: buckets: items: $ref: '#/components/schemas/PromptCacheBucket' title: Buckets type: array estimate: default: true description: >- Always true: the savings are an estimate, never what a provider billed. title: Estimate type: boolean group_by: items: type: string title: Group By type: array prices: description: The price of every model the estimate used. items: $ref: '#/components/schemas/ModelPriceOut' title: Prices type: array prices_as_of: description: When the product's table was taken from the public price lists. title: Prices As Of type: string since: format: date title: Since type: string until: format: date title: Until type: string required: - since - until - group_by - buckets - prices - prices_as_of title: PromptCacheReport type: object Problem: additionalProperties: false description: RFC 9457 problem details; `code` comes from the versioned error catalog. properties: code: title: Code type: string detail: anyOf: - type: string - type: 'null' default: null title: Detail request_id: anyOf: - type: string - type: 'null' default: null title: Request Id status: title: Status type: integer title: title: Title type: string type: default: about:blank title: Type type: string required: - title - status - code title: Problem type: object PromptCacheBucket: additionalProperties: false properties: cache_write_tokens: description: Input tokens written to the cache. title: Cache Write Tokens type: integer cached_tokens: description: Input tokens the provider read from its prompt cache. title: Cached Tokens type: integer calls: description: Agent turns whose model call reported its usage. title: Calls type: integer day: anyOf: - format: date type: string - type: 'null' title: Day estimated_savings_micros: anyOf: - type: integer - type: 'null' description: >- An estimate, in millionths of a US dollar: cached tokens at the input price minus the cached price, less the write premium, by the price of each call's model. Null when no call of the bucket has a price. title: Estimated Savings Micros hit_rate: anyOf: - type: number - type: 'null' description: '`cached_tokens` over `prompt_tokens`; null without tokens.' title: Hit Rate model: anyOf: - type: string - type: 'null' title: Model prompt_tokens: description: Every input token of those calls, cached ones included. title: Prompt Tokens type: integer provider: anyOf: - type: string - type: 'null' title: Provider source_id: anyOf: - format: uuid type: string - type: 'null' title: Source Id unpriced_calls: default: 0 description: >- Calls of models without a price in either table: left out of the estimate. title: Unpriced Calls type: integer vendor: anyOf: - type: string - type: 'null' description: From the source configuration; "" when none. title: Vendor required: - calls - prompt_tokens - cached_tokens - cache_write_tokens title: PromptCacheBucket type: object ModelPriceOut: additionalProperties: false properties: cache_write: title: Cache Write type: number cached_input: title: Cached Input type: number input: description: USD per million input tokens. title: Input type: number model: title: Model type: string provider: title: Provider type: string table: description: >- `product`: the product's table of public prices; `space`: the space's settings. enum: - product - space title: Table type: string required: - provider - model - input - cached_input - cache_write - table title: ModelPriceOut type: object securitySchemes: sourceKey: type: http scheme: bearer description: nia_sk_... personToken: type: http scheme: bearer bearerFormat: JWT ````