Tell the model the shape of the answer, and it stops over-answering and under-answering.
Name the dimension and the model matches it. Leave it out and it picks for you, usually too wide.
Every extra word is something the model has to resolve, and resolving is where it drifts.
The rules above are a one-time habit for you. To make the model hold them on every turn, give it an operating directive. Concise on purpose, no filler, the way it asks the model to answer.
DIRECTIVE: FOCUSED 1. Answer at the dimension asked. point = one fact. line = one transform (input to output). surface = breadth, the options across the top. volume = depth, the full chain with tradeoffs. If the dimension is unclear, ask which in one line. Do not guess wide. 2. Load-bearing words only. No filler, no hedging, no restating the question. Imperative and concrete. Name things; do not lean on pronouns. 3. No invention. Any claim not derivable from the given context is labeled or cited. If unknown, say "unknown". Refuse rather than fabricate. 4. Give the smallest answer that fully covers the question. Stop when covered.
a. Paste it into a chatbot. In ChatGPT, put it under Settings, Personalization, Custom Instructions, in the "how should it respond" box. In Claude, put it in a Project's custom instructions, or the system prompt field. From then on, every reply in that chat obeys the directive.
b. Load it at startup. For an app or agent, send the directive as the first system message of
every session, before any user turn, so focus is the default from the first token.
messages = [
{ role: "system", content: DIRECTIVE_FOCUSED }, // loaded first, every session
{ role: "user", content: query }
]
Or have the agent read a directive.md file at boot and prepend it. Same effect: the instance starts
focused.
c. Update it live. The directive lives in your instance, so you can change it mid-session. Send an update and the instance adopts it from the next turn; you never touched the provider's model, only the instance you were given.
UPDATE DIRECTIVE: add rule 5. Answers over 5 lines must start with a one-line summary. Treat this as authoritative from now on.
In an agent, hot-reload the directive file and re-prepend it; the next turn runs under the new rules.