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Synthesize many documents into one brief

Point Cowork at a stack of documents and get back one coherent brief — the throughline, the conflicts, the gaps — instead of reading all of them yourself and hoping you held it in your head.

Stage: Cowork · For: Maker, Manager · Level: Intermediate · Time: 15 min

When to use this

Five docs say overlapping things. A SharePoint folder, a few email threads, a couple of reports — and you need one answer that reconciles them. Reading them all is hours; holding the contradictions in your head is impossible. Cowork does the synthesis job end to end: it reads across the set, finds the common thread, surfaces where the sources disagree, and hands you a single brief you can actually act on.

For managers this is the "give me the truth across all of this" button; for makers it's a preview of the reasoning an agent will do for you on a schedule once you build one.

What you'll need

  • M365 Copilot license with Cowork access
  • The document set — files, threads, or a folder; the more they overlap, the more synthesis earns its keep
  • The question you actually need answered, so Cowork synthesizes toward a decision

Try it now — the prompt

Point Cowork at the set and tell it what the brief is for:

Read all of these and write me one brief: what they agree on, where they conflict,
and what's missing. Lead with a 3-sentence bottom line, then the supporting detail,
and cite which source each claim came from. Flag anything where the sources
disagree so I know what to dig into.

Why this works: it names the job (synthesize, don't summarize each), the structure (bottom-line- first), a traceability requirement (cite the source per claim), and asks Cowork to surface conflicts — which is the part you can't get from reading any single doc.

Step by step

  1. Give Cowork the full set and send the prompt. It reads across every source and works the synthesis as one multi-step job, not a doc-by-doc summary.
  2. Read the bottom line first, then the conflicts. The three-sentence top is the answer; the conflict flags are where you decide what still needs a human.
  3. Trace the claims that matter. For any load-bearing statement, follow the citation back to the source before you rely on it. Synthesis is only as good as its grounding.
  4. Tighten it for how you'll use it: 
    Cut it to one page, drop anything all the sources already agree on, and turn the
conflicts into a short "open questions" list I can take into the review.

Screenshots

Captured live in Microsoft 365 Copilot (Work mode). The product UI moves fast — if what you see differs, trust the numbered steps above, which we keep current.

Three conflicting sources pasted in with a request for one cited brief Paste the full set of sources and tell Cowork what the brief is for — bottom-line-first, cited per claim, with conflicts flagged.

The brief leading with a three-sentence bottom line and where the sources agree The brief leads with a three-sentence bottom line, then lays out where the sources agree — each point cited back to its source.

The brief surfacing where the sources conflict and what is missing Then it surfaces exactly where the sources conflict and what's missing — the part you can't get from reading any single document.

Make it better

Synthesis is a starting point, not an endpoint: - Aim it at a decision. "Based on all of this, what would you recommend and why?" — then pressure-test the recommendation against the conflicts it found. - Make it repeatable. "Every Monday, re-run this over the latest versions and tell me only what changed." You've just described an agent's job. - Widen the aperture. Add a competitor report or an external source and ask it to reconcile internal and outside views into one picture.

📚 Learn more. The M365 Copilot resources hub covers how Cowork handles multi-source work across the Copilot experience. For a parallel community treatment of delegating end-to-end jobs to Cowork, Sean Galliher's Cowork Cookbook (community-built, unofficial — not a Microsoft resource) is worth a read.

Watch out for

  • Synthesis isn't truth — it's a reading. Cowork reconciles what the sources say; if they're all wrong in the same way, the brief inherits that. Treat the bottom line as a strong hypothesis.
  • Citations are the safety rail — use them. A synthesized claim with no traceable source is the one to distrust. If you can't follow it back, don't build on it.
  • Watch for quiet flattening. When sources conflict, a synthesis can average them into a blandly "balanced" line that hides a real disagreement. The conflict flags exist so that doesn't happen — read them.

Where this leads (the ramp)

You've now had Cowork do the reasoning across a whole document set — and you probably noticed you'd want this same job run on a schedule, over a known set of sources, without re-explaining it each time. That standing, source-scoped reasoner is exactly what you build next: Stage 4 · Agent Builder.

Next: Agent Builder → Build a team-knowledge agent over a SharePoint site

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