How to Write a Technical Spec with AI Agents

You start building. Three days in, you realize the feature doesn't handle a key edge case. You rebuild. Another two days gone. That's a week lost on something a 30-minute document could have caught.

A technical spec is that document. And with AI agents, writing one takes less time than the Slack thread you'd normally have about it.

What Is a Technical Spec?

A technical spec is a short document that defines what you're building, why it exists, how it works, and what's out of scope. It's not a 40-page enterprise artifact. For a solo founder, it's 400-600 words that force you to think before you touch the code.

A good spec answers four questions: What's the problem? What are we building? How does it work? What can go wrong?

If you can't answer all four, you're not ready to build yet.

How to Write a Technical Spec with AI Agents

Here's the process that works well with the Technical Writer agent in the Engineering department.

1. State the problem: Write one or two sentences describing what's broken or missing. Be specific. "Users can't reset their password without contacting support" is good. "Improve user experience" is not.

2. List the requirements: Give the Technical Writer your problem statement and ask it to generate functional requirements. Review and cut anything you don't need this week.

3. Draft the solution: Ask the agent to describe how the feature works from the user's perspective. What does the user do? What does the system do in response? Keep it in plain language, not code.

4. Identify edge cases: Ask the agent what could go wrong. What happens if the session expires mid-flow? What if the input is empty? What if the third-party API is down? You want this list before you write a single line of code.

5. Define what's out of scope: Write down what you are not building in this version. This is the most important section for a solo founder. Scope creep is what kills shipping velocity.

6. Set acceptance criteria: One or two conditions that define when the feature is done. "User can reset password via email link without contacting support" is a done condition. "Looks good" is not.

If you're not sure which feature to spec first, the Sprint Prioritizer in the Product department can help you narrow your backlog before you write a spec.

Real Example: Shipping a Password Reset Feature

You're building a SaaS product alone. Users keep emailing about the broken password reset flow. You want to fix it this week.

You open your dashboard and assign a task to the Technical Writer agent:

"Write a technical spec for a self-service password reset feature. Users should be able to reset their password via email link. We're using Supabase Auth. No SMS or social login for now."

The agent returns a draft in about 4 minutes. It includes the full user flow (request reset, receive email, click link, enter new password, confirm), the database fields involved, edge cases (expired links, invalid tokens, rate limiting), and a clear out-of-scope list (magic links, SSO, password strength requirements).

You spend 10 minutes reviewing and editing. Now you have a spec that takes you from "I think I know what to build" to "I know exactly what to build and what to skip."

Total time: 15 minutes. Time saved: at least a day of rebuilding.

Common Mistakes Founders Make With Technical Specs

Writing the spec after you've already started coding. You have an idea, you get excited, you open your editor. The spec ends up describing what you built, not what you planned to build. That's documentation, not a spec.

Making it too long. A technical spec is not a product requirements document. Three pages is too long. If your spec exceeds one page, you're including too much implementation detail. Let the code handle the implementation.

Skipping the out-of-scope section. Every feature has a version two that feels like it should be in version one. Writing down what you're not building prevents you from adding it mid-build.

Leaving acceptance criteria vague. "Feature works correctly" is not an acceptance criterion. Write the specific condition that tells you the feature is complete. You need this to stop yourself from tweaking indefinitely.

Bottom Line

A technical spec takes 15-20 minutes to write with an AI agent. Not having one costs you days. The spec doesn't need to be perfect. It needs to be specific enough that you know what you're building and what you're skipping.

The Technical Writer in the Engineering department handles the drafting. You handle the decisions. That's the right split.

---

Ready to put this into practice? Browse the departments and start with whichever handles your biggest current bottleneck.