How to Use Ellipsis AI Agent to Explore a Codebase

Review comments are only half of Ellipsis. The other half is an agent you can ask about the codebase — useful when you join a project, inherit a service, or need to confirm how a feature actually works before shipping. This guide is about using it as a code-exploration tool, not a linter.

Why use an AI agent to read code?

Because grep tells you where a symbol is, not how it behaves end to end. An agent that has indexed the repo can trace a request from route to database and summarise the flow. For a new codebase, that turns a day of reading into an hour of questions.

How do you ask good questions?

1. Start broad: “What does this service do and what are its entry points?”
2. Narrow to flow: “Trace what happens when a user resets a password.”
3. Ask for files: “Which files would I change to add a new field to the user model?”
4. Verify against the code before acting — cross-check the files it names.

Treat answers as a map, not the territory. The agent can miss dynamic imports and config-driven behaviour, so open the files it points to.

How does this change onboarding?

• New hires get answers before interrupting a teammate.
• Reviewers check a claim in the PR against the agent before arguing about it.
• Maintainers audit dead code by asking what still calls a module.

The habit that pays off is asking before editing, not after — it catches wrong assumptions early.

How reliable are the answers?

Good on structure and local logic; weaker on anything that depends on runtime config, feature flags or external services it cannot see. If a question hinges on production behaviour, the agent gives a hypothesis and you still need a log or a test to confirm it. Never merge a risky change on the strength of an agent answer alone.

When is it the wrong tool?

Skip it for repos with heavy generated code or monorepo sprawl where indexing is partial, and for legal or licensing questions it cannot judge. It also cannot replace reading critical security paths yourself. Use it to navigate, then verify.

Quick Summary

• Ellipsis also works as an agent that answers questions about your repo.
• Ask broad, then trace flows, then request the exact files to change.
• It speeds onboarding and lets reviewers verify claims before debating them.
• Answers are a map: strong on structure, weak on runtime and external behaviour.
• Skip it on heavily generated monorepos and never merge risky changes on its word alone.