AI explicitly acknowledges knowledge gaps rather than guessing

System prompts that include "always provide a complete, detailed answer" without qualification effectively prohibit the AI from acknowledging knowledge gaps — creating a forcing function for fabrication. When the model cannot say "I don't know," it generates a plausible-sounding answer instead. For users who cannot independently verify AI output, this is indistinguishable from a correct answer. OWASP LLM09 identifies this as a misinformation risk category. The fix is low-cost — a single sentence of explicit permission — but the absence of it structurally removes the model's most important safety valve against confabulation.

Add explicit "I don't know" permission to your system prompt:

const systemPrompt = `
...existing instructions...
If you are not confident in an answer, say so directly. It is better to say
"I'm not sure about this" or "I don't have reliable information on that"
than to provide an answer you cannot verify.
`

Audit for any instruction that reads "always provide a complete answer" or "never say you don't know" — these must be removed or qualified with an exception for genuine knowledge gaps.