Claude Haiku 4.5 vs Claude Opus 4.7 for Constrained Rewriting
In our testing Claude Opus 4.7 is the better choice for Constrained Rewriting. Opus scores 4 versus Claude Haiku 4.5's 3 on the constrained rewriting benchmark (rank 6 vs 32 of 53), delivering more reliable compression inside hard character limits. The win is driven by Opus's higher creative problem solving (5 vs 4) and better safety calibration (3 vs 2), plus a larger context capacity — all of which improve nuanced, compact rewrites. Haiku 4.5 remains the pragmatic pick when cost or per-request latency matters: it exposes explicit control parameters and costs much less ($1 input / $5 output per million tokens versus Opus's $5 / $25).
anthropic
Claude Haiku 4.5
Benchmark Scores
External Benchmarks
Pricing
Input
$1.00/MTok
Output
$5.00/MTok
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anthropic
Claude Opus 4.7
Benchmark Scores
External Benchmarks
Pricing
Input
$5.00/MTok
Output
$25.00/MTok
modelpicker.net
Task Analysis
Constrained Rewriting requires precise compression: preserve meaning, tone, and required content while strictly meeting hard character limits. Key capabilities are (1) faithfulness to source text, (2) structured-output and format control to enforce length and schema, (3) long-context handling when source material is large, (4) creative problem solving to find concise phrasings, and (5) safety calibration to avoid dropping or altering required content. Because there is no third‑party external benchmark provided for this task in the payload, our internal constrained rewriting scores are the primary signal: Claude Opus 4.7 scores 4 and Claude Haiku 4.5 scores 3 on the constrained rewriting test. Supporting evidence from our internal suite: structured output is tied at 4 for both models, faithfulness and long context are tied at 5, but Opus outperforms Haiku on creative problem solving (5 vs 4) and safety calibration (3 vs 2). Haiku lists explicit supported parameters (include_reasoning, structured outputs, temperature, tools, etc.), giving developers more direct prompt/control knobs; Opus's supported parameters are not listed in our data. Context windows differ markedly (Haiku 200k tokens vs Opus 1,000,000), which favors Opus when the source exceeds Haiku's practical input size.
Practical Examples
When Opus 4.7 shines: • Tight executive summaries that must retain multiple facts under a 300‑character limit — Opus's higher creative problem solving (5 vs 4) and constrained rewriting score (4 vs 3) produce denser, accurate compressions. • Large-source condensation — Opus's 1,000,000 token context window avoids source truncation, reducing faithfulness risk for long documents. When Haiku 4.5 shines: • High-volume batch rewriting (microcopy, SMS, metadata) where cost and latency dominate — Haiku costs $1 per million input tokens and $5 per million output tokens versus Opus at $5/$25, making Haiku roughly 20% of Opus's price in our datasets. • Precise, repeatable formatting workflows where the listed parameter controls (structured outputs, stop, temperature, etc.) let engineers enforce length and style systematically. Comparative numbers to ground choices: constrained rewriting 4 vs 3 (Opus vs Haiku), creative problem solving 5 vs 4, safety calibration 3 vs 2, context windows 1,000,000 vs 200,000 tokens, and identical structured output (4) and faithfulness (5).
Bottom Line
For Constrained Rewriting, choose Claude Haiku 4.5 if you need a much lower-cost, fast option with explicit parameter controls for high-volume or latency-sensitive pipelines. Choose Claude Opus 4.7 if you need higher-quality compression under tight character limits, better creative compacting, and the ability to handle very large source documents — Opus wins by 1 point in our constrained rewriting tests (4 vs 3).
How We Test
We test every model against our 12-benchmark suite covering tool calling, agentic planning, creative problem solving, safety calibration, and more. Each test is scored 1–5 by an LLM judge. Read our full methodology.