---
title: "How to Validate Your AI Agent's Plan Before It Writes Code"
description: "The cheapest change is the one you make before the code exists. Here's how to have your AI agent sketch its plan on screen, correct it visually, and only then let it build."
date: 2026-06-08
updated: 2026-06-08
canonical: https://screentack.com/blog/validate-ai-agent-plan-before-writing-code
---

# How to Validate Your AI Agent's Plan Before It Writes Code

The cheapest change you can make is the one *before* the code exists. Once an agent has generated a real page or component, correcting it means regenerating it — and paying for that round-trip every time. The fix is to review the **plan**, not the diff. Here's the workflow, exactly as the clip above shows it.

## Why this works

An AI coding agent's expensive failure mode is building the wrong thing because it misread your intent. The misunderstanding is identical whether you catch it early or late — but the *cost* is not. Caught at the plan stage, it's a couple of corrected marks. Caught in the generated artifact, it's a throwaway build. For the token math behind that, see [annotate, don't regenerate](/blog/annotate-dont-regenerate-token-cost).

## What you need

- An AI coding agent that speaks **MCP** (e.g. Claude Code).
- [Screentack](/) running, which hosts the agent↔human visual tools over MCP — free. This is the [bidirectional visual feedback loop](/blog/bidirectional-visual-feedback-for-ai-coding-agents) in practice.

## The steps

1. **Ask for the plan, visually.** Before it builds, tell the agent: *"Sketch your layout plan on screen so I can correct it first."* Instead of generating code, it calls `annotate_understanding` and draws labeled regions on the live page — nav, hero, CTA, feature grid.
2. **Read the plan on the real page.** The agent's intent is now visible as editable marks, in context — not buried in a description.
3. **Correct it where it's wrong.** Annotate feedback directly on screen: "hero should be full-width," "make the CTA a bigger primary button," "3-up, not 4." Send it back.
4. **Let the agent read your feedback.** It calls `get_annotation_feedback`, reads your corrections, and confirms the revised plan.
5. **Now let it build** — once, against the plan you already agreed on.

You spent a handful of marks to get alignment that would otherwise have cost several full generate-and-eyeball cycles.

## When to use it

Reach for plan-first validation whenever the agent is about to produce something **structural** — a page layout, a system or architecture diagram, a workflow or flowchart, a component tree, a refactor, a schema. The agent can sketch any of these as labeled shapes for you to correct first. The bigger the thing it's about to generate, the more a wrong assumption costs, and the more you save by catching it on the plan. (For the broader category, see [bidirectional visual feedback for AI coding agents](/blog/bidirectional-visual-feedback-for-ai-coding-agents); for why one-way screenshots leave this gap, [why screenshots aren't enough](/blog/your-coding-agent-should-annotate-back).)

## The takeaway

Don't review your agent's work after it builds — review its *plan* before it does. It's faster, it's cheaper, and it's the difference between an agent that guesses and one that checks.

> Get your agent to show its plan before it writes a line of code. [Download Screentack](/#waitlist) — a free 7-day trial, then $29 once.