Build reliable system prompts from structured sections
A vague one-line system message (“you are a helpful assistant”) leaves the model guessing. This builder lets you compose a system prompt from clearly labelled sections — role, context, constraints, output format and tone — toggle the ones you need, reorder them, and copy a clean, ready-to-paste prompt string. Structuring the prompt this way makes the model’s behaviour more predictable and the prompt far easier to maintain.
How it works
Each field maps to a named section. As you type, the tool assembles them in the order you choose, giving each a clear heading so the model can tell role from rule from format. The constraints box is special: every non-empty line becomes its own bulleted rule, because models follow an explicit numbered or bulleted list of rules more reliably than the same rules hidden inside a paragraph. Empty sections are dropped automatically, so you only ship what you filled in, and the “Copy” button puts the finished prompt on your clipboard.
Tips and notes
Keep the role short and concrete — “a senior tax accountant for UK sole traders” beats “an expert”. Put your hardest, must-never-break rules in constraints, one per line, in plain imperative language. Use output format to pin down structure (JSON shape, markdown headings, max length) — this is where most reliability wins come from. Tone is for voice, not substance. Reorder so the most load-bearing sections sit near the top, since instructions early in the system message tend to be weighted most heavily. The whole thing runs locally, so it is safe to paste in proprietary context.