What is System Prompt?
The persistent instruction block prepended to every request that sets role, rules, and output format. It outranks user text in well-built stacks, which is why builders version it like code, not copy.
Related terms
Few-Shot Prompting
Showing the model two or more input-output examples inside the prompt so it imitates the pattern. Examples beat paragraphs of instruction for format, tone, and edge-case handling in builder and support tasks.
Prompt Caching
Reusing priced prefixes of a prompt across requests so repeated system context bills at the reduced cached rate. Long builder sessions benefit most, since stable instructions and history prefixes repeat every turn.
Prompt Injection Defense
Techniques that stop untrusted content from hijacking model instructions: delimiting retrieved text, least-privilege tools, and confirmation before side effects. Treat all pasted or fetched content as data, never orders.
Temperature
Sampling randomness for generation: low values make output focused and repeatable, high values make it varied and surprising. BYOB chat configs default near 0.5 while tool calls use 0.3 for steadier structured actions.
Thinking Budget
The token allowance reserved for internal model reasoning before answering. Larger budgets suit hard multi-step problems; BYOB prices thinking tokens separately so runaway reasoning shows up in metering.
Structured Output
Forcing model replies into a machine-readable shape such as JSON with fixed fields. Required wherever AI output feeds code, databases, or UI components, since free text breaks parsers the moment formatting drifts.