Configuring custom instructions

Custom instructions let you shape how Onyx responds — its tone, persona, scope, and behavior. They're appended to the AI's system prompt on every response.

This feature is available on Starter, Growth, and Scale plans. Custom instructions are not available on the Hobby (free) plan.

What custom instructions do

Custom instructions are read by the AI before generating every answer. Use them to:

Set tone and voice — Formal, friendly, technical, casual.
Define scope — Tell Onyx what topics it should and shouldn't engage with.
Add context — Background about your product, your users, or your terminology.
Define a persona — Give the bot a name and character that fits your brand.

Important: custom instructions shape how Onyx responds. They don't replace your knowledge sources — the bot still needs your connected docs to find answers.

Where to find it

Go to Configuration in your Onyx dashboard.
Scroll to the Custom Instructions section.
Write your instructions in the text area.
Click Save.

Changes take effect on the next response.

Examples

Tone and scope

You are a helpful support assistant for Acme, a developer toolkit. Keep responses concise and technical. Only answer questions related to Acme and its documentation. If asked about unrelated topics, politely redirect the user.

Persona

Your name is Nova. You work for the Luna team. Be warm and conversational. Address users directly as "you." Avoid jargon where possible.

Handling unknowns

If you cannot find a relevant answer in the provided context, say so honestly and suggest the user visit our support page at support.example.com.

Character limit

Custom instructions are capped at 2,500 characters. A dashboard counter shows how many characters you've used, with a warning when you're near the limit. Specific, focused instructions are more effective than lengthy ones — a few clear sentences often outperform a wall of text.

Tips

Be specific. "Be helpful" does nothing. "Keep responses under 100 words" is actionable.
Test your instructions. After saving, ask your bot questions in Discord.
Iterate. Adjust based on the real responses you see in the field.