How to Write a Coding Agent Brief It Can Execute

Key takeaways

• A coding agent brief needs seven parts: goal, context, constraints, files and repos, acceptance criteria, verification steps, and stop conditions.
• Each brief section blocks a specific failure mode: ambiguity, missing context, no completion test, or drift between queued prompts.
• Acceptance criteria must be executable, naming exact commands, file paths, and expected output the agent can verify itself.
• For parallel agents, scope each brief to one repo area and one branch, and sequence dependent work after merging.
• When chaining sessions, restate changed state and criteria at every handoff, since the agent has no memory of prior steps.

A coding agent completes your task without follow-up only when the brief specifies the goal, the constraints, the acceptance criteria, and what to do when it hits ambiguity. Most prompts specify the goal alone, so the agent guesses at the rest and you find out at review. This guide shows the same task briefed two ways, maps each rewrite to a named failure mode, and gives you a reusable template.

Why does a coding agent fail even with a good prompt?

When an agent goes off track, the model is rarely the cause. The brief is. A prompt that reads clearly to you still leaves the agent guessing about scope, file structure, and what "done" means, so it fills the gaps with plausible-but-wrong choices.

The four failure modes: ambiguity, missing context, no completion test, drift

Ambiguity means two valid readings of the same instruction. The agent picks one; you meant the other.

Missing context hits hardest in multi-step work. One practitioner describing chained agent sessions put it plainly: "How do you handle context degradation? If the model messes up the refactoring even a little bit in the first step... the next prompts in the queue are just going to" inherit the error (r/opensource on running AI agents).

No completion test leaves the agent declaring victory on its own word. Drift compounds all three: each queued prompt inherits the previous session's mistakes.

The fix is a brief format, not a better prompt. We break down the format on the Aerunit blog; the next section covers what a brief adds beyond a prompt.

What does a coding agent brief need that a prompt doesn't?

A prompt says what to do. A brief contains everything the agent needs to finish without you: scope, context, acceptance criteria, and a definition of done. Skip any one of them and you become the glue between steps, pasting the next prompt into one of six terminals.

Scope

Name the files, functions, and repos the agent may touch, and what it must leave alone. Unbounded scope is where drift between queued prompts starts.

Context

State the file structure, relevant conventions, and why the task exists. Agents that guess at structure propagate that guess into every downstream session.

Acceptance criteria

Write checks the agent can run itself: tests, commands, expected output. "It works" is not a criterion.

Definition of done

Say what happens at the end: which branch, what commit message, what to do on failure. Tools like Aerunit, Conductor, or Devin differ in orchestration, but none can invent a done state you never wrote (https://aerunit.ai/cloud-coding-agents-compared).

What is a reusable brief template for coding agents?

The seven-part template

A brief that survives a queue has seven parts: goal, context, constraints, files and repos, acceptance criteria, verification steps, and stop conditions. The goal is one sentence stating what exists when the agent finishes. Context names the decisions already made so the agent doesn't re-litigate them. Constraints list what must not change.

Files and repos point at exact paths, which matters when you dispatch work through Cursor Cloud Agents and the agent starts with no memory of your terminal session. Acceptance criteria are checkable statements the agent can test itself against. Verification steps tell it how: run the tests, hit the endpoint, review the diff. Stop conditions say when to halt instead of improvising.

The long paragraph worth quoting on its own: the sections exist because each one blocks a specific failure mode. Context prevents drift between queued prompts, because the third prompt in a queue inherits nothing from the first unless you write it down. Acceptance criteria prevent silent incompleteness, the "how do I know it's actually done?" problem. Verification steps prevent an agent from declaring victory on code it never ran. Skip a section and you become the glue again, pasting clarifications between six terminals.

What to leave out

Leave out background narrative, alternative approaches you considered, and anything you would say verbally. We keep briefs that worked on the Aerunit blog so the template gets reused instead of rewritten per task.

Before and after: the same task briefed two ways

Before: the brief that invites clarification

"Add pagination to the issues list. Keep it consistent with the rest of the app."

The agent guesses the page size, the query param, whether to paginate server- or client-side, and which "rest of the app" pattern to copy. It picks something plausible. Your next queued prompt assumes a different choice, and drift compounds down the queue while you review six terminals of output.

After: the brief that runs unattended

"Add cursor-based pagination to GET /api/issues (default 25, ?cursor= param). Paginate the Linear-style issues table client-side from that endpoint. Copy the pagination row pattern from app/components/TaskTable.tsx. Done when: 25 issues render per page, next/prev buttons work, and pnpm test issues passes. If the component pattern doesn't fit, stop and report rather than inventing one."

What each change fixed

Change in the brief	Failure mode it prevents
Named the endpoint, defaults, and param	Agent invents an API shape the next prompt doesn't match
Pointed at a concrete file to copy	Context degradation across steps: the "consistent with the app" reference decays
Verifiable acceptance criteria	Silent incompleteness: "done" you can check, not vibes
Explicit stop-and-report rule	Agent papering over a bad assumption instead of surfacing it

The rewrite is longer, but you write it once instead of pasting follow-ups into every session. The same discipline applies when one brief touches several repos; see cross-repo changes with coding agents.

How do you write acceptance criteria an agent can verify itself?

"Works correctly" is not a criterion; it is a hope. An agent can only verify what it can run, so every criterion should resolve to a command, a file path, or an observable output. If the agent cannot check it without asking you, it belongs in the brief as a test, not in a follow-up prompt.

Executable criteria vs descriptive criteria

Descriptive criteria tell the agent what good looks like. Executable criteria tell it how to prove it. Compare:

• Descriptive: "The export endpoint handles large files."
• Executable: "pytest tests/test_export.py -k large_file passes; the generated CSV opens with csv.reader and has 10,001 rows."

Three rules get you there. First, name the exact command and expected exit state. Second, name exact file paths, because an agent that guesses the location of a fixture will invent one. Third, state what must not change, like "no changes outside src/export/", so review the diff is quick.

For chained sessions, this matters more: each follow-up prompt inherits degraded context, so a verifiable checklist is the only contract that survives handoff. Anthropic's Claude Code documentation on subagents and task handling describes this pattern of delegating bounded, verifiable work (Anthropic docs). More brief templates with executable criteria are in our guides.

How do you brief coding agents that run in parallel?

Parallel agents collide when two briefs touch the same files. Each agent works on its own worktree and branch, but git only saves you at merge time. Scope the work before you queue it.

One brief, one repo area, one branch

Write the file scope into the brief itself: "only files under src/billing/, do not touch src/api/ routes." If two tasks both need the same module, that is a dependency, not a coincidence. Either merge them into one brief or sequence them. Keep each branch small enough that a reviewer can read the diff in one sitting.

Sequencing dependent work

Never queue a dependent prompt behind an agent that might fail. Run the foundation task, review the diff, merge, then brief the next task against the updated main. Chained prompts on stale worktrees are how context degradation compounds: the second agent inherits the first agent's mistakes as ground truth. A short "blocked by: task X, merged to main" line in each brief makes the ordering explicit and keeps your agent fleet honest about what each one can actually see.

How do briefs change when you chain agent sessions?

A single-task brief can assume the agent knows nothing. A chained brief cannot assume anything at all, because step N inherits whatever mess step N-1 made. One misunderstood file structure early on, and every queued prompt afterward builds on a wrong model of the repo.

Restating state at every handoff

Treat each handoff like a Linear issue description: self-contained, current, and written for someone with no memory of the conversation (Linear docs). At every step boundary, restate three things: what the previous session actually changed, what the diff shows versus what was intended, and the exact acceptance criteria for the next step. Never reference "as discussed" or "the plan from step 1"; the agent has no access to it.

The honest caveat: restating state costs tokens and feels redundant. The alternative is worse. When one agent silently drifts, you become the glue between every step, re-explaining context slightly differently each time with no record of where it broke.

How do you know a brief was good before the agent runs?

Run it through a pre-flight check. Five questions, one minute:

1. Could a new hire execute this without asking you anything?
2. Does every acceptance criterion name a file, command, or observable output?
3. Is the scope one reviewable diff, not three?
4. If this is step N in a chain, does it restate the paths and conventions earlier steps touched, rather than assuming the agent remembers?
5. If the agent silently skips half the work, what in the brief would catch it? If nothing would, the criteria aren't verifiable yet.

Orchestration tools can enforce some of this. Aerunit scopes work from Linear into briefs for Cursor Cloud Agents and keeps agents busy across repos, so a weak brief surfaces as a failed check instead of a wasted queue slot. It will not fix vague criteria for you; the checklist still does that. Conductor, Devin, Agentastic, Factory, and Orgabot occupy the same space, and the same rule applies: tooling catches drift, but only a sharp brief prevents it.

FAQ

How long should a coding agent brief be?

Long enough to cover all seven parts: goal, context, constraints, files and repos, acceptance criteria, verification steps, and stop conditions. The pagination rewrite in this guide runs about four sentences, yet it removes every guess the one-liner left open. Aim for the shortest brief that still names exact paths, runnable checks, and what to do on ambiguity.

Can I just paste a Linear ticket into a coding agent?

Rarely as-is. A ticket describes the problem for humans who share your context; an agent shares none of it. Convert it by adding the pieces tickets usually omit: exact file paths, executable acceptance criteria, and a stop condition. Tools like Aerunit scope Linear work into briefs for this reason, but even manually, ten minutes of rewriting beats a queue of follow-up prompts.

Do different coding agents need different briefs?

The brief content stays the same; the delivery changes. Cursor Cloud Agents start with no memory of your terminal session, so paths and conventions must be written down rather than assumed. Devin and Conductor differ in orchestration, not in what they need from you. None of them can invent a definition of done you never wrote, so the seven parts apply everywhere.

What do I do when the agent still asks clarifying questions?

Treat each question as a missing brief section, not a one-off answer. If it asks about page size, your acceptance criteria were not checkable. If it asks where a file lives, your paths were not exact. Fix the template so the next brief closes the gap, and add a stop-and-report rule so ambiguity surfaces before the agent improvises.