> ## Documentation Index > Fetch the complete documentation index at: https://openrouter-d02e98a0-mintlify-7021d5f4.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # AnthropicImageBlockParam - Go SDK > AnthropicImageBlockParam type definition The Go SDK and docs are currently in beta. Report issues on [GitHub](https://github.com/OpenRouterTeam/go-sdk/issues). ## Fields | Field | Type | Required | Description | Example | | -------------- | ------------------------------------------------------------------------------------------------------------------ | -------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------- | | `CacheControl` | [\*components.AnthropicCacheControlDirective](/client-sdks/go/api-reference/models/anthropiccachecontroldirective) | :heavy\_minus\_sign: | Enable automatic prompt caching. When set at the top level, the system automatically applies cache breakpoints to the last cacheable block in the request. Currently supported for Anthropic Claude models. | `{"type": "ephemeral"}` | | `Source` | [components.AnthropicImageBlockParamSource](/client-sdks/go/api-reference/models/anthropicimageblockparamsource) | :heavy\_check\_mark: | N/A | | | `Type` | [components.AnthropicImageBlockParamType](/client-sdks/go/api-reference/models/anthropicimageblockparamtype) | :heavy\_check\_mark: | N/A | |