On February 24, 2025, Anthropic announced Claude 3.7 Sonnet, describing it as its most intelligent model to date and the first hybrid reasoning model on the market. The framing is pointed: unlike reasoning models shipped as separate products, Anthropic argues reasoning should be an integrated capability of frontier models rather than a separate model entirely — because just as people use a single brain for both quick responses and deep reflection, the capability belongs inside one model.

One model, two modes

Concretely, hybrid reasoning means the same model caneitherreturn a near-instant responseoremit extended, step-by-step thinking that is made visible to the user. In standard mode, Anthropic says Claude 3.7 Sonnet represents an upgraded version of Claude 3.5 Sonnet. In extended thinking mode, it self-reflects before answering, which improves its performance on math, physics, instruction-following, coding, and many other tasks. One practical detail: prompting works similarly in both modes, so existing prompts largely carry over instead of requiring a separate reasoning-specific rewrite.

The thinking budget is an API dial

The most consequential mechanism for builders is control overhow longthe model thinks. Through the API, you can tell Claude to think for no more than N tokens, for any value of N up to its output limit of 128K tokens. That sentence is the feature: the thinking budget is not a separate model or product tier but a tunable cap set per request, letting developers trade off speed and cost for quality of answer. Deliberation is something you pay for only when you ask for it.

Thinking tokens are billed as output

The pricing follows the same logic. In both standard and extended thinking modes, Claude 3.7 Sonnet has the same price as its predecessors: $3 per million input tokens and $15 per million output tokens — which includes thinking tokens. The clause to underline iswhich includes thinking tokens. Because the budget can climb toward the 128K output limit, and every reasoning token is billed at the output rate, a generous budget becomes a direct, meterable line item. Cost discipline and thinking-budget discipline are the same discipline.

Availability determines where you can even test the dial: Claude 3.7 Sonnet ships on all Claude plans plus the Claude Developer Platform, Amazon Bedrock and Google Cloud's Vertex AI. Crucially,extended thinking mode is available on every surface except the free Claude tier, so budget tuning requires a paid tier.

Benchmarks and third-party validation

Anthropic claims state-of-the-art results on two agentic evaluations. OnSWE-bench Verified— which tests a model's ability to resolve real-world software issues — Claude 3.7 Sonnet reaches62.3%out of the box, rising to70.3% with a custom scaffold. For context, the chart places Claude 3.5 Sonnet (new) at 49.0% and several rivals in a tight cluster near 49%. The appendix explains the gap behind those first two numbers: the vanilla 62.3% counts problems that are unsolvable on Anthropic's infrastructure as failures to maintain parity with the official leaderboard, corresponding to 63.7% on the subset that works on its infrastructure; the 70.3% figure adds parallel attempts, discards patches that break visible regression tests, and ranks survivors with a scoring model.

OnTAU-bench, which tests agents on user-and-tool interactions, Claude 3.7 Sonnet scores81.2% on the retail taskversus 71.5% for Claude 3.5 Sonnet (new) and 73.5% for OpenAI o1; on the airline task it scores58.4%versus 48.8% and 54.2% respectively.

Naming third-party firms is part of the pitch: on early testing, Cursor called it once again best-in-class for real-world coding tasks; Cognition found it far better than any other model at planning code changes and handling full-stack updates; Vercel highlighted exceptional precision for complex agent workflows; Replit deployed it to build sophisticated web apps and dashboards from scratch; and in Canva's evaluations it consistently produced production-ready code with far fewer errors.

Claude Code

Alongside the model, Anthropic introducedClaude Code, its first agentic coding tool, in a limited research preview. It is described as an active collaborator that can search and read code, edit files, write and run tests, commit and push code to GitHub, and use command-line tools — keeping the developer in the loop at every step. The concrete claim: in early testing, Claude Code completed tasks in a single pass that would normally take 45+ minutes of manual work.

Building responsibly

Two safety points stand out. First, calibration: Claude 3.7 Sonnet makes more nuanced distinctions between harmful and benign requests, reducing unnecessary refusals by45%compared to its predecessor. Second, the system card addresses emerging risks that come with computer use, particularly prompt-injection attacks, and explains how Anthropic evaluates these vulnerabilities and trains Claude to resist and

The practical takeaway: choosing a budget and what it costs

The decision rule is unusual in its simplicity, because Anthropic exposes one lever rather than a menu. You choose two things: mode (standard or extended thinking) and, in the API, the cap N on thinking tokens, anywhere up to the 128K output limit.

Latency- or cost-sensitive paths (autocomplete, routing, simple transforms): stay in standard mode or set a low N. A small budget buys speed.
Hard reasoning (math, physics, complex instruction-following): raise N. Anthropic notes extended thinking gives a notable boost in math and science, and that it optimized somewhat less for competition puzzles in favor of real-world tasks — which is why the benchmark story leans on coding and agentic evaluations.
What it costs: the rate is flat — $3 per million input tokens and $15 per million output tokens, with thinking tokens billed as output. There is no separate reasoning surcharge and no cheaper thinking tier. Roughly 1,000 thinking tokens add about $0.015 to a request; the point is that the bill scales with how much you let the model deliberate.

Put differently: the thinking budget is the cost dial, and the cost dial is the speed dial. Developers get to decide, per request, how much reflection is worth paying for.

Sources: Anthropic — Introducing Claude 3.7 Sonnet.

Category: Review

Claude 3.7 Sonnet: Hybrid Reasoning, Thinking Budgets and the Cost of Reasoning

Category: Review

Claude 3.7 Sonnet: Hybrid Reasoning, Thinking Budgets and the Cost of Reasoning