Two kinds of instruction, two different jobs
When you direct an agent, not every instruction is the same kind of thing. Some things are true every time the agent works: how you want files named, what currency to use, which documents to flag as suspicious. Others are true only today: which batch of documents you are processing, how many files are in it, what period they cover.
These two kinds of instruction have different names and different places. Your standing preferences describe how the work should always be done. Your brief describes this particular job. Mixing them up is one of the most common reasons an agent behaves inconsistently.
Standing preferences: what is always true
A standing preference is a guideline that applies every single time the agent runs, regardless of the task in front of it. It does not change from month to month. In the monthly financial-documents run, a standing preference sounds like this: file every document by calendar month. You do not want to say that in January, forget it in February, and then wonder in March why your files are in a different order. It goes into your standing knowledge once, and the agent carries it into every run automatically.
Other standing preferences for that same job might include: always convert amounts to pounds sterling, always flag any document without a supplier name, always produce a summary count at the end. These are your standards. They are part of who the agent is for this work.
The brief: what is true only today
A brief covers the specifics of the current run and nothing else. It tells the agent what it is working on right now. For the same financial-documents job, the brief sounds like this: this batch covers March; there are 61 documents in the folder. Next month the brief changes: April, 44 documents. The month after: May, 58. The standing preferences stay exactly the same.
This is the separation that keeps the agent reliable. If you write this batch covers March into your standing preferences, the agent will say March in April, May, and every month that follows until you remember to change it. That is not a brief; that is a mistake embedded in your standards.
Why the separation matters
When standing preferences and the brief are kept apart, two things become easier. First, you only write your standards once. Second, when something goes wrong, you know immediately where to look: was the agent’s permanent knowledge wrong, or was the brief for this particular run unclear? Those are two completely different problems with two completely different fixes.
If you collapse them into one block of instructions, you lose that diagnostic clarity. Every month becomes a fresh opportunity to accidentally introduce last month’s specifics into this month’s job.
The takeaway
Before you write any instruction for your agent, ask: is this always true, or is it true only for this run? If it is always true, it belongs in your standing preferences. If it is true only today, it belongs in the brief. Keep them in separate places, and your agent’s behaviour will be consistent every time you run it.