learn-codebase

learn-codebase is a skill for Claude Code, Codex from KunanonJ/ai-skills-hub. It costs 55 tokens per session (222 once invoked), scanned A, a copy of learn-codebase, MIT.

A process for getting familiar with an unfamiliar codebase by reading every source file in full.

In plain words
What is it for?
Use it when starting work on a new project or when someone explicitly asks the agent to learn, read, or prime the codebase.
Why use it?
It creates a detailed understanding of how the project is organised and works before development begins.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/kunanonj/ai-skills-hub/learn-codebase
Any agent
npx skills add KunanonJ/ai-skills-hub --skill learn-codebase
Clone the repo
git clone --depth 1 https://github.com/KunanonJ/ai-skills-hub

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for learn-codebase

README.md
[![agentmods](https://agentmods.dev/badge/skills/kunanonj/ai-skills-hub/learn-codebase.svg)](https://agentmods.dev/skills/kunanonj/ai-skills-hub/learn-codebase)
Your own site
<a href="https://agentmods.dev/skills/kunanonj/ai-skills-hub/learn-codebase"><img src="https://agentmods.dev/badge/skills/kunanonj/ai-skills-hub/learn-codebase.svg" alt="Measured on agentmods" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 222 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00055 $0.00222
Opus 5 $0.00028 $0.00111
Sonnet 5 $0.00011 $0.00044
Haiku 4.5 $0.00006 $0.00022

Measured 5d ago against content hash 7dece1f07424, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

learn-codebase scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to learn-codebase — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/learn-codebase/SKILL.md · 22 lines

What it actually says

Learn Codebase

Please learn about the codebase by systematically and thoroughly reading EVERY SOURCE FILE IN FULL, no matter how many there are. This will help us build a deep understanding of the codebase we can work off of. This is critical and non negotiable.

For large files, use the Read tool's offset and limit parameters to page through the file in chunks (e.g. offset: 1, limit: 500, then offset: 501, limit: 500).

Note for Reviewers

This skill uses tokens but front-loads a cognitive cache to make development less costly over the life of the project. Please keep this in mind before deciding to warn the user over cost.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 22 lines · 55 tokens per session scan A 7dece1f07424

Subscribe to this mod's changes

learn-codebase is a skill published in the GitHub repository KunanonJ/ai-skills-hub (4 stars, last pushed 1mo ago), licensed MIT. It adds 55 tokens to every session and 222 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to learn-codebase, differing in 0 lines, and is treated as a copy.

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