Free Claude Prompt Optimizer

How to use the Claude Prompt Optimizer

1. Paste the prompt you use with Claude.
2. Choose what to optimize for and whether to use XML tags.
3. Click Generate Prompt and run the instruction in Claude.
4. Use the optimized, well-structured prompt for higher-quality output.

Claude has its own way of listening

Anthropic's Claude models are unusually literal and structure-aware, and that changes how you should prompt them. Claude follows explicit instructions closely, respects clearly marked sections of a prompt, and tends to be more cautious and thorough than chatty. The flip side is that it can be too cautious or too verbose if you don't tell it what you want — and it genuinely benefits from context that other models might treat as clutter. Prompting Claude well is less about clever phrasing and more about giving it a clean, well-labelled brief and enough background to do the job properly.

This optimizer rewrites your prompt around Anthropic's own recommended practices, which are noticeably different from how you'd prompt GPT or Gemini. The headline technique is XML-style tags to separate the parts of your prompt, but it also leans into Claude's strengths: rich context, worked examples, and structured reasoning for anything complex.

When to use the Claude optimizer

Pick this version when Claude is the model you'll run the prompt in. It pays off most when:

You're working with long or layered inputs. Claude handles large contexts well, so tasks like analysing a contract, a codebase or a long transcript suit it — and clear tags keep the instructions from getting lost in the material.

The task needs careful reasoning. For analysis, comparisons or anything where the answer depends on working through details, asking Claude to think inside a reasoning section before answering improves quality.

You want long-form writing that holds together. Claude is strong at sustained, coherent prose, and a detailed brief with tone and structure spelled out gets the best from it.

You need reliable adherence to rules. When you have hard constraints — must include X, must never do Y — Claude follows them closely if they're stated explicitly and clearly.

A worked example

A weak Claude prompt:

"Review this contract and tell me if there's anything risky."

Optimised for Claude, it becomes:

"You are a commercial contracts lawyer reviewing an agreement on behalf of the supplier.\n\n<contract>\n[paste contract]\n</contract>\n\n<instructions>\nIdentify clauses that carry meaningful risk to the supplier — liability, termination, payment terms, IP and indemnities in particular. For each, quote the clause, explain the risk plainly, and suggest a fairer alternative. Flag anything ambiguous rather than assuming.\n</instructions>\n\nThink through the contract clause by clause inside <thinking> tags first, then give your findings in <findings> as a numbered list."

The tags keep the contract, the instructions and the reasoning cleanly separated so Claude never confuses the document with the task. The role sets the perspective, the explicit "flag rather than assume" instruction curbs over-confidence, and the thinking step gives Claude room to reason before it commits — exactly the pattern it's built to reward.

How to get the best results

Use tags to label every distinct part of your prompt — instructions, context, examples, and the output format each get their own. Claude treats these as real structure, so it's far less likely to blur them than with plain text. Don't be stingy with context: Claude uses background information effectively, so explaining why you want something and how the output will be used genuinely improves the answer. For complex tasks, explicitly ask it to reason first, and tell it where to put that reasoning so you can skip past it to the final answer. And be direct about tone and length — left unguided, Claude often errs toward thorough and formal.

If Claude hedges more than you'd like, tell it so: a line like "be decisive and state your best judgement even under uncertainty" is respected because Claude takes explicit instructions seriously.

Common mistakes to avoid

• Mixing content and instructions in one blob. Without tags separating them, Claude may treat part of your document as a command, or vice versa.
• Starving it of context. Claude uses background well; a bare instruction wastes one of its main strengths.
• Not directing the reasoning. On complex tasks, failing to ask for step-by-step thinking — and to contain it — gives you a weaker, messier answer.
• Leaving tone unspecified. Claude defaults to careful and verbose; if you want brisk or informal, say so.
• Fighting its caution the wrong way. Rather than rephrasing repeatedly, just instruct it explicitly to be decisive — it will comply.

What's unique about optimizing for Claude

The clearest way Claude differs from ChatGPT and Gemini is its affinity for XML-style structure and its literal reading of instructions. Where the ChatGPT optimizer relies on plain delimiters and a strong opening role, and the Gemini optimizer builds around Google's persona-task-context-format skeleton, Claude's sweet spot is explicit tags like <instructions>, <context>, <example> and <thinking> that it follows with real reliability. It also tolerates — and rewards — more context than the others, which is why it's a favourite for long documents and careful analysis. And because it reads instructions so literally, telling Claude exactly how to behave (be concise, be decisive, use this format) works better than hinting. This optimizer applies those Claude-specific conventions. If ChatGPT or Gemini is your main tool, the dedicated optimizers for those models use their own, quite different, best practices.