Context engineering: a complete AI briefing, from sources to draft

“Write a customer announcement about our new delivery windows” sounds like a clear request. Then you attach the project folder: an old launch plan, a meeting note proposing a delay, and a release decision. Which date should appear in the email?

What context engineering means

The writing is the easy part. The useful work is deciding what the assistant needs to know before it writes.

Context engineering means selecting and arranging the information an AI receives for a task. That includes your instructions and the material it will use: documents, conversation history and, when available, results from tools. Anthropic’s guide describes this broader work of managing context, beyond writing the prompt itself.

For an everyday writing task, you can start with a small, complete briefing. Below is one you can copy into a new chat, followed by the customer announcement it should support.

Give each source a job

Our fictional company, Parcelwise, is preparing to offer two-hour delivery windows. Customers need an update, but the launch date is undecided. The communications lead has three short records:

An old plan explains why 12 October appeared in earlier discussions. A meeting note records a suggestion to move to 19 October. An approved communication decision establishes what the company can tell customers now.

Keeping the first two records is useful here: they explain the competing dates. They do not get an equal vote on what to announce. If you were simply writing from a settled release note with no conflicting history, you could leave the old planning material out.

This is the practical difference between asking for better wording and giving a better briefing. “Be accurate” does not tell the assistant whether a date was proposed, approved or withdrawn. The source labels and excerpts do.

Copy this complete briefing

The fictional exercise takes place on 10 October 2026. All the information needed for the draft is included below; no search or connected workspace is required. The expected output that follows is an editorial example, not a reported model test.

Task: Draft an email to Parcelwise customers about upcoming two-hour delivery windows. Today is 10 October 2026.

Audience and voice: Existing customers who currently see four-hour delivery windows. Be clear and helpful. Avoid launch hype and internal project language.

How to use the sources: The communications lead has checked the status labels below. Source C governs this announcement. Sources A and B explain earlier planning; neither establishes a launch date. Use only facts supplied here. Do not search for additional facts.

Source A — Initial project plan Written: 20 September 2026 Status: superseded planning document; not approved for announcement Excerpt: “Target 12 October 2026 for two-hour delivery windows. Customers currently receive four-hour windows.”

Source B — Operations meeting note Written: 8 October 2026 Status: proposal; no launch approval recorded Excerpt: “The team proposed 19 October 2026 as an alternative launch date. Operations still needs to confirm readiness.”

Source C — Customer communication decision Written and approved: 9 October 2026 Owner: communications lead Status: approved for this customer update Excerpt: “We are preparing two-hour delivery windows. The launch date is not confirmed; neither 12 nor 19 October is scheduled. Customers will continue to receive four-hour windows for now. Existing bookings are unchanged. Customers do not need to act. We will email another update on 15 October 2026, even if the launch date is still undecided.”

Return two clearly separate parts: 1. CUSTOMER EMAIL: subject and complete draft, about 80–120 words. State what is coming, what remains unchanged, whether customers need to act and when they will hear from us. Do not mention the rejected planning dates or invent a launch date or benefits. 2. PRIVATE CONFIRMATION NOTE: identify the source for the key facts and say what must be confirmed before announcing a launch date. This note is for the communications lead, not the customer email.

Draft only. Do not send anything.

What a supported announcement looks like

Customer email

Subject: An update on our planned two-hour delivery windows

We’re preparing to offer two-hour delivery windows at Parcelwise. We haven’t confirmed a launch date yet, so your deliveries will continue to use four-hour windows for now.

Your existing bookings are unchanged, and you don’t need to take any action.

We’ll email you another update on 15 October 2026, even if we’re still working toward a confirmed launch date. That is the date of our next update, not the start of the new windows.

Thank you, The Parcelwise team

Private confirmation note

Source C supports the planned two-hour windows, the unchanged four-hour service and existing bookings, no customer action, and the 15 October update. Sources A and B contain earlier planning dates; Source C explicitly says neither is scheduled. Before drafting a launch announcement, obtain a confirmed launch date and an updated communication decision. Operations readiness remains unresolved in Source B.

The useful result is a finished customer update, not a refusal to write because one fact is missing. It answers the questions customers can reasonably have today without turning the next communication date into a launch promise. The internal follow-up stays separate.

Check the promises, not the phrasing

If you try the briefing, your assistant may choose different sentences. Review three concrete things: does it keep the launch date unconfirmed, preserve the existing service and bookings, and identify 15 October as an update date only? Check that the private note has not slipped into the email.

A polished sentence such as “Enjoy shorter waits from 15 October” would fail twice: it invents a launch date and a benefit the supplied records do not establish. You would need to correct the draft before sending it.

The labels also need to be true. Calling a document “approved” in a prompt does not approve it in your company. Here, the communications lead has already checked the records. When you adapt the example, do that source check yourself rather than asking the model to guess who made the decision.

Use the briefing on your next task

Replace Parcelwise’s records with the few documents that answer your audience’s questions. Include the current facts, enough history to explain a real conflict, and any missing fact that changes what you can say. Specify the deliverable and show where private follow-up belongs.

Manual selection takes effort, but it gives you a clear view of what the assistant received. A connected assistant can retrieve documents for repeated work; you will still need to check that the relevant version reached the task. A larger archive does not, by itself, resolve an undecided launch date.

If answers disagree even with the same briefing, use the inconsistent-answer guide to investigate that separate problem. For this task, start with the deliverable: could you finish the customer email from the facts you supplied? If you cannot, improve the briefing before polishing the prompt.

Prepared by HeyBrain Editorial Team with AI assistance. Parcelwise, its documents and the sample output are fictional teaching examples. The linked primary documentation was checked on 12 October 2026.