Adaptive thinking

This feature is eligible for Zero Data Retention (ZDR). When your organization has a ZDR arrangement, data sent through this feature is not stored after the API response is returned.

Adaptive thinking is the recommended way to use extended thinking with Claude Opus 4.7, Claude Opus 4.6, and Claude Sonnet 4.6, and is the default mode on Claude Mythos Preview (where it auto-applies whenever thinking is unset). Instead of manually setting a thinking token budget, adaptive thinking lets Claude dynamically determine when and how much to use extended thinking based on the complexity of each request. On Claude Opus 4.7, adaptive thinking is the only supported thinking mode; manual thinking: {type: "enabled", budget_tokens: N} is no longer accepted.

Adaptive thinking can drive better performance than extended thinking with a fixed budget_tokens for many workloads, especially bimodal tasks and long-horizon agentic workflows. No beta header is required.

If your workload requires predictable latency or precise control over thinking costs, extended thinking with budget_tokens is still functional on Claude Opus 4.6 and Claude Sonnet 4.6 but is deprecated and no longer recommended. See the warning below.

Supported models

Adaptive thinking is supported on the following models:

Claude Mythos Preview (claude-mythos-preview), adaptive thinking is the default; thinking: {type: "disabled"} is not supported
Claude Opus 4.7 (claude-opus-4-7), adaptive thinking is the only supported thinking mode. Thinking is off unless you explicitly set thinking: {type: "adaptive"} in your request; manual thinking: {type: "enabled"} is rejected with a 400 error.
Claude Opus 4.6 (claude-opus-4-6)
Claude Sonnet 4.6 (claude-sonnet-4-6)

thinking.type: "enabled" and budget_tokens are deprecated on Opus 4.6 and Sonnet 4.6 and will be removed in a future model release. Use thinking.type: "adaptive" with the effort parameter instead. Existing budget_tokens configurations are still functional but no longer recommended; plan to migrate.

Older models (Sonnet 4.5, Opus 4.5, etc.) do not support adaptive thinking and require thinking.type: "enabled" with budget_tokens.

How adaptive thinking works

In adaptive mode, thinking is optional for the model. Claude evaluates the complexity of each request and determines whether and how much to use extended thinking. At the default effort level (high), Claude almost always thinks. At lower effort levels, Claude may skip thinking for simpler problems.

Adaptive thinking also automatically enables interleaved thinking. This means Claude can think between tool calls, making it especially effective for agentic workflows.

How to use adaptive thinking

Set thinking.type to "adaptive" in your API request:

Adaptive thinking with the effort parameter

You can combine adaptive thinking with the effort parameter to guide how much thinking Claude does. The effort level acts as soft guidance for Claude's thinking allocation:

Effort level	Thinking behavior
`max`	Claude always thinks with no constraints on thinking depth. Available on Claude Mythos Preview, Claude Opus 4.7, Claude Opus 4.6, and Claude Sonnet 4.6.
`xhigh`	Claude always thinks deeply with extended exploration. Available on Claude Opus 4.7.
`high` (default)	Claude always thinks. Provides deep reasoning on complex tasks.
`medium`	Claude uses moderate thinking. May skip thinking for very simple queries.
`low`	Claude minimizes thinking. Skips thinking for simple tasks where speed matters most.

Streaming with adaptive thinking

Adaptive thinking works seamlessly with streaming. Thinking blocks are streamed via thinking_delta events just like manual thinking mode:

Adaptive vs manual vs disabled thinking

Mode	Config	Availability	When to use
Adaptive	`thinking: {type: "adaptive"}`	Claude Mythos Preview (default), Opus 4.7 (only mode), Opus 4.6, Sonnet 4.6	Claude determines when and how much to use extended thinking. Use `effort` to guide.
Manual	`thinking: {type: "enabled", budget_tokens: N}`	All models except Claude Opus 4.7 (rejected). Deprecated on Opus 4.6 and Sonnet 4.6 (consider adaptive mode instead).	When you need precise control over thinking token spend.
Disabled	Omit `thinking` parameter or pass `{type: "disabled"}`	All models except Claude Mythos Preview	When you don't need extended thinking and want the lowest latency.

Adaptive thinking is available on Claude Mythos Preview, Claude Opus 4.7, Opus 4.6, and Sonnet 4.6. On Mythos Preview, adaptive thinking is the default and applies automatically whenever thinking is unset. On Claude Opus 4.7, adaptive thinking is the only supported mode and type: "enabled" with budget_tokens is rejected. Older models only support type: "enabled" with budget_tokens. On Opus 4.6 and Sonnet 4.6, type: "enabled" with budget_tokens is still functional but deprecated.

Interleaved thinking availability by mode:

Adaptive mode: Interleaved thinking is automatically enabled on Claude Mythos Preview, Claude Opus 4.7, Opus 4.6, and Sonnet 4.6. On Mythos Preview and Opus 4.7, inter-tool reasoning always lives inside thinking blocks.
Manual mode on Sonnet 4.6: Interleaved thinking works via the interleaved-thinking-2025-05-14 beta header.
Manual mode on Opus 4.6: Interleaved thinking is not available. If your agentic workflow requires thinking between tool calls on Opus 4.6, use adaptive mode.

Important considerations

Validation changes

When using adaptive thinking, previous assistant turns don't need to start with thinking blocks. This is more flexible than manual mode, where the API enforces that thinking-enabled turns begin with a thinking block.

Prompt caching

Consecutive requests using adaptive thinking preserve prompt cache breakpoints. However, switching between adaptive and enabled/disabled thinking modes breaks cache breakpoints for messages. System prompts and tool definitions remain cached regardless of mode changes.

Tuning thinking behavior

Adaptive thinking's triggering behavior is promptable. If Claude is thinking more or less often than you'd like, you can add guidance to your system prompt:

Extended thinking adds latency and should only be used when it
will meaningfully improve answer quality — typically for problems
that require multi-step reasoning. When in doubt, respond directly.

Steering Claude to think less often may reduce quality on tasks that benefit from reasoning. Measure the impact on your specific workloads before deploying prompt-based tuning to production. Consider testing with lower effort levels first.

Cost control

Use max_tokens as a hard limit on total output (thinking + response text). The effort parameter provides additional soft guidance on how much thinking Claude allocates. Together, these give you effective control over cost.

At high and max effort levels, Claude may think more extensively and can be more likely to exhaust the max_tokens budget. If you observe stop_reason: "max_tokens" in responses, consider increasing max_tokens to give the model more room, or lowering the effort level.

Working with thinking blocks

The following concepts apply to all models that support extended thinking, regardless of whether you use adaptive or manual mode.

Summarized thinking

With extended thinking enabled, the Messages API for Claude 4 models returns a summary of Claude's full thinking process. Summarized thinking provides the full intelligence benefits of extended thinking, while preventing misuse. This is the default behavior on Claude 4 models when the display field on the thinking configuration is unset or set to "summarized". On Claude Opus 4.7 and Claude Mythos Preview, display defaults to "omitted" instead, so you must set display: "summarized" explicitly to receive summarized thinking.

Here are some important considerations for summarized thinking:

You're charged for the full thinking tokens generated by the original request, not the summary tokens.
The billed output token count will not match the count of tokens you see in the response.
On Claude 4 models, the first few lines of thinking output are more verbose, providing detailed reasoning that's particularly helpful for prompt engineering purposes. Claude Mythos Preview summarizes from the first token, so its thinking blocks do not show this verbose preamble.
As Anthropic seeks to improve the extended thinking feature, summarization behavior is subject to change.
Summarization preserves the key ideas of Claude's thinking process with minimal added latency, enabling a streamable user experience and easy migration from Claude Sonnet 3.7 to Claude 4 and later models.
Summarization is processed by a different model than the one you target in your requests. The thinking model does not see the summarized output.

Claude Sonnet 3.7 continues to return full thinking output.

In rare cases where you need access to full thinking output for Claude 4 models, contact our sales team.

Controlling thinking display

The display field on the thinking configuration controls how thinking content is returned in API responses. It accepts two values:

"summarized": Thinking blocks contain summarized thinking text. See Summarized thinking for details. This is the default on Claude Opus 4.6, Claude Sonnet 4.6, and earlier Claude 4 models.
"omitted": Thinking blocks are returned with an empty thinking field. The signature field still carries the encrypted full thinking for multi-turn continuity (see Thinking encryption). This is the default on Claude Opus 4.7 and Claude Mythos Preview.

Setting display: "omitted" is useful when your application doesn't surface thinking content to users. The primary benefit is faster time-to-first-text-token when streaming: The server skips streaming thinking tokens entirely and delivers only the signature, so the final text response begins streaming sooner.

Here are some important considerations for omitted thinking:

You're still charged for the full thinking tokens. Omitting reduces latency, not cost.
If you pass thinking blocks back in multi-turn conversations, pass them unchanged. The server decrypts the signature to reconstruct the original thinking for prompt construction (see Preserving thinking blocks). Any text you place in the thinking field of a round-tripped omitted block is ignored.
display is invalid with thinking.type: "disabled" (there is nothing to display).
When using thinking.type: "adaptive" and the model skips thinking for a simple request, no thinking block is produced regardless of display.

The signature field is identical whether display is "summarized" or "omitted". Switching display values between turns in a conversation is supported.

On Claude Opus 4.7, thinking.display defaults to "omitted". Thinking blocks still appear in the response stream, but their thinking field is empty unless you explicitly opt in. This is a silent change from Claude Opus 4.6, where the default was "summarized". To restore summarized thinking text on Claude Opus 4.7, set thinking.display to "summarized" explicitly:

thinking = {
    "type": "adaptive",
    "display": "summarized",
}

For code examples and streaming behavior with display: "omitted", see Controlling thinking display on the extended thinking page. The examples there use type: "enabled"; with adaptive thinking, use:

thinking = {"type": "adaptive", "display": "omitted"}

Thinking encryption

Full thinking content is encrypted and returned in the signature field. This field is used to verify that thinking blocks were generated by Claude when passed back to the API.

It is only strictly necessary to send back thinking blocks when using tools with extended thinking. Otherwise you can omit thinking blocks from previous turns. If you pass them back, whether the API keeps or strips them depends on the model: Opus 4.5+ and Sonnet 4.6+ keep them in context by default; earlier Opus/Sonnet models and all Haiku models strip them. See context editing to configure this.

If sending back thinking blocks, we recommend passing everything back as you received it for consistency and to avoid potential issues.

Here are some important considerations on thinking encryption:

When streaming responses, the signature is added via a signature_delta inside a content_block_delta event just before the content_block_stop event.
signature values are significantly longer in Claude 4 models than in previous models.
The signature field is an opaque field and should not be interpreted or parsed.
signature values are compatible across platforms (Claude APIs, Amazon Bedrock, and Vertex AI). Values generated on one platform will be compatible with another.

Pricing

For complete pricing information including base rates, cache writes, cache hits, and output tokens, see the pricing page.

The thinking process incurs charges for:

Tokens used during thinking (output tokens)
Thinking blocks from prior assistant turns kept in context: only the last turn on earlier Opus/Sonnet models and all Haiku models; all turns by default on Opus 4.5+ and Sonnet 4.6+ (input tokens)
Standard text output tokens

When extended thinking is enabled, a specialized system prompt is automatically included to support this feature.

When using summarized thinking:

Input tokens: Tokens in your original request (excludes thinking tokens from previous turns)
Output tokens (billed): The original thinking tokens that Claude generated internally
Output tokens (visible): The summarized thinking tokens you see in the response
No charge: Tokens used to generate the summary

When using display: "omitted":

Input tokens: Tokens in your original request (same as summarized)
Output tokens (billed): The original thinking tokens that Claude generated internally (same as summarized)
Output tokens (visible): Zero thinking tokens (the thinking field is empty)

The billed output token count will not match the visible token count in the response. You are billed for the full thinking process, not the thinking content visible in the response.

Additional topics

The extended thinking page covers several topics in more detail with mode-specific code examples:

Tool use with thinking: The same rules apply for adaptive thinking: preserve thinking blocks between tool calls and be aware of tool_choice limitations when thinking is active.
Prompt caching: With adaptive thinking, consecutive requests using the same thinking mode preserve cache breakpoints. Switching between adaptive and enabled/disabled modes breaks cache breakpoints for messages (system prompts and tool definitions remain cached).
Context windows: How thinking tokens interact with max_tokens and context window limits.

Next steps

Extended thinking

client = anthropic.Anthropic()

response = client.messages.create(
    model="claude-opus-4-7",
    max_tokens=16000,
    thinking={"type": "adaptive"},
    messages=[
        {
            "role": "user",
            "content": "Explain why the sum of two even numbers is always even.",
        }
    ],
)

for block in response.content:
    if block.type == "thinking":
        print(f"\nThinking: {block.thinking}")
    elif block.type == "text":
        print(f"\nResponse: {block.text}")

client = anthropic.Anthropic()

response = client.messages.create(
    model="claude-opus-4-7",
    max_tokens=16000,
    thinking={"type": "adaptive"},
    output_config={"effort": "medium"},
    messages=[{"role": "user", "content": "What is the capital of France?"}],
)

print(response.content[0].text)

client = anthropic.Anthropic()

with client.messages.stream(
    model="claude-opus-4-7",
    max_tokens=16000,
    thinking={"type": "adaptive"},
    messages=[
        {
            "role": "user",
            "content": "What is the greatest common divisor of 1071 and 462?",
        }
    ],
) as stream:
    for event in stream:
        if event.type == "content_block_start":
            print(f"\nStarting {event.content_block.type} block...")
        elif event.type == "content_block_delta":
            if event.delta.type == "thinking_delta":
                print(event.delta.thinking, end="", flush=True)
            elif event.delta.type == "text_delta":
                print(event.delta.text, end="", flush=True)