AI Engineering

How to Document a Codebase for AI Agents

By nimblabs editorial··7 min read
Structured codebase documentation optimized for an AI coding agent

Key takeaways

  • AI-oriented docs prioritize high-signal facts over prose narratives.
  • Cover architecture, entry points, conventions, constraints, and landmines.
  • Point to where things live instead of duplicating the code.
  • Keep it compact — bloated docs waste the agent's context budget.
  • Store it where the agent reads it every session and keep it current.

Why AI docs are different

Documentation for humans can be narrative and exhaustive. Docs for an AI agent need to be high-signal and compact, because the agent reads them into a finite context window where every token competes for attention.

The goal isn't completeness — it's giving the agent exactly the facts it needs to act correctly.

What to include

Cover the architecture at a glance, the main entry points, the conventions you enforce, the hard constraints, and the landmines (intentional weirdness not to 'fix'). That's what keeps an agent aligned.

Leave out long tutorials and anything the agent can read straight from the code.

Point, don't duplicate

Reference where things live ('auth logic is in lib/auth, all HTTP goes through lib/http') rather than pasting implementations. The agent can open the files; it just needs the map.

Duplicated code in docs goes stale fast and burns context.

Keep it compact

A bloated doc is self-defeating: it pushes the important facts out of the window and dilutes attention. Ruthlessly trim to what changes the agent's behavior.

If a line wouldn't affect how the agent acts, it probably doesn't belong.

Put it where agents read it

Store the doc in the project memory file (or referenced from it) so the agent loads it every session, and review it like code so it stays current.

Documentation the agent never sees might as well not exist.

Frequently asked questions

How is documenting for AI different from for humans?+

AI docs are high-signal and compact rather than narrative and exhaustive, because they're read into a finite context window where every token competes for attention.

What should AI codebase docs include?+

Architecture overview, entry points, conventions, hard constraints, and landmines — plus pointers to where code lives, not copies of it.

Where should I put docs for an AI agent?+

In the project memory file (or referenced from it) so the agent reads them each session, and keep them current via code-style review.

Can docs be too long for an AI agent?+

Yes. Bloated docs waste context budget and dilute attention; trim to what actually changes the agent's behavior.

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