Anthropic cacheControl Option not being sent to Anthropic API

[SouthCentralCode]

Description

Package Versions:
"@ai-sdk/anthropic": "^1.2.10",
"ai": "^4.0.22",

My code setting up the system message:

  const systemMessages = [
    {
      role: 'system' as const,
      content: systemPrompt,
      providerOptions: {
        anthropic: { cacheControl: { type: 'ephemeral' } },
      },
    },
  ];

* My system prompt is approx 36K characters.

The code runs fine, returning a response and the following usage info..

"finishReason":"stop","usage":{"promptTokens":11323,"completionTokens":467,"totalTokens":11790},"
however on the second run, ran 30 seconds later to ensure the cache is primed, you can see the prompt caching results is empty... (although the usage tokens are as above)

,"providerMetadata":{"anthropic":{"cacheCreationInputTokens":0,"cacheReadInputTokens":0}},"experimental_providerMetadata":{"anthropic":{"cacheCreationInputTokens":0,"cacheReadInputTokens":0}},"isContinued":false}]}

To try and figure out what was going on, i've routed it through Helicone to see the raw request...

and you can see that the cache control properties are not present..

Helicone raw request:

{
  "model": "claude-3-5-haiku-20241022",
  "max_tokens": 1000,
  "temperature": 0,
  "system": [
    {
      "type": "text",
      "text": "You are an exper... [40,000 characters more]"
    }
  ],
  "messages": [
    {
      "role": "assistant",
      "content": [
        {
          "type": "text",
          "text": "Hello... I'm  your smart assistant. Ask me anything and i'll try to answer your questions. "
        }
      ]
    },
    {
      "role": "user",
      "content": [
        {
          "type": "text",
          "text": "Summarize the strengths and weaknesses"
        }
      ]
    }
  ]
}

This worked ok in "@ai-sdk/anthropic": "^1.0.6",

[SouthCentralCode]

I can confirm that this code using the native anthropic sdk: returns prompt caching usage info as expected...

const client = new Anthropic();

    const response = await client.messages.create({
      model: ModelNames.CLAUDE_3_5_HAIKU,

      max_tokens: 1024,
      system: [

        {
          type: 'text',
          text: systemPrompt,  // Same prompt as used above.
          cache_control: { type: 'ephemeral' },
        },
      ],
      messages: [
        {
          role: 'assistant',
          content: 'what can i so for you?.',
        },
        {
          role: 'user',
          content: 'Summarise the transcript.',
        },
      ],
    });

    console.log(response.usage);
    return response;

[Nazariy995]

Having the same issue actually!

issue is that it is not caching at all!

[jawwadurrehman]

I've raised the issue here in case it’s helpful for the team:
🔗 #5942

Context:
This issue relates to how the Vercel AI SDK handles providerOptions specifically cacheControl when using the streamText function with messages that include parts (structured content). Currently, these options don’t seem to be forwarded correctly to the provider, resulting in unexpected behavior such as caching not being applied, even when explicitly configured.

[lgrammel]

Please ensure that you have a large enough prompt:

The minimum cacheable prompt length is:

1024 tokens for Claude 3.7 Sonnet, Claude 3.5 Sonnet and Claude 3 Opus
2048 tokens for Claude 3.5 Haiku and Claude 3 Haiku
Shorter prompts cannot be cached, even if marked with cacheControl. Any requests to cache fewer than this number of tokens will be processed without caching.

See https://sdk.vercel.ai/providers/ai-sdk-providers/anthropic#cache-control

[SouthCentralCode]

thanks for the response, My system prompt is approx 8000 tokens.

…

On Thu, 24 Apr 2025 at 10:37, Lars Grammel ***@***.***> wrote: *lgrammel* left a comment (vercel/ai#5883) <#5883 (comment)> Please ensure that you have a large enough prompt: The minimum cacheable prompt length is: 1024 tokens for Claude 3.7 Sonnet, Claude 3.5 Sonnet and Claude 3 Opus 2048 tokens for Claude 3.5 Haiku and Claude 3 Haiku Shorter prompts cannot be cached, even if marked with cacheControl. Any requests to cache fewer than this number of tokens will be processed without caching. See https://sdk.vercel.ai/providers/ai-sdk-providers/anthropic#cache-control — Reply to this email directly, view it on GitHub <#5883 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AF6BKQHCARLFT52VI6S3IVT23CWGJAVCNFSM6AAAAAB3TA2IU2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDQMRWHE4DIOBZGI> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[Nazariy995]

yes same for us! Turns out we had to convert messages to CoreMessages!

We thought it was converted by Default!

const messages = convertToCoreMessages(uiMessages);

This now worked! It's back caching!

@SouthCentralCode @zeke

[SouthCentralCode]

ok thats interesting... and thanks...

My only cacheControl was set on the systemMessages... not uimessages

and I was spreading the incoming messages using...

const aggMessages = [...systemMessages, ...uiMessages] and prompt caching would not work..

changing it to...

const aggMessages = [...systemMessages, ...convertToCoreMessages(uiMessages)] and prompt caching works as expected here.

Seems strange that the type of UIMessages would affect the properties of the system model, anyway! onwards!

thanks all.