second-brain

second-brain is a skill for Claude Code from coreyhaines31/makerskills. It costs 238 tokens per session (2,884 once invoked), scanned A, original, MIT.

A workflow for maintaining a personal Second Brain: an Obsidian or Markdown notebook organised into raw sources, linked topic pages, and generated outputs. It follows the Karpathy LLM Wiki structure, where related ideas are compiled into reusable pages.

In plain words
What is it for?
Use it to capture articles, highlights, ideas, and notes; compile them into linked topic pages; query the knowledge base; check its structure; and create summaries or analyses.
Why use it?
It separates original notes from organised knowledge and generated work, making the notebook easier to update, search, and connect without losing source material.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions CLAUDE.md; built for gbrain.

Part of the makerskills plugin — 21 skills shipped together

Good fit Use it to capture articles, highlights, ideas, and notes; compile them into…

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/coreyhaines31/makerskills/second-brain
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.

Any agent
npx skills add coreyhaines31/makerskills --skill second-brain
Clone the repo
git clone --depth 1 https://github.com/coreyhaines31/makerskills

Made for: Claude Code.

Or install makerskills, the plugin that ships this one along with the rest of its 21 skills.

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 second-brain

README.md
[![agentmods](https://agentmods.dev/badge/skills/coreyhaines31/makerskills/second-brain.svg)](https://agentmods.dev/skills/coreyhaines31/makerskills/second-brain)
Your own site
<a href="https://agentmods.dev/skills/coreyhaines31/makerskills/second-brain"><img src="https://agentmods.dev/badge/skills/coreyhaines31/makerskills/second-brain.svg" alt="Measured on agentmods" height="20"></a>
Per session 238 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,884 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found 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 $0.00238 $0.02884
Opus 5 $0.00119 $0.01442
Sonnet 5 $0.00048 $0.00577
Haiku 4.5 $0.00024 $0.00288

Measured 7d ago against content hash 1a76730e1be3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

second-brain 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 7d 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.

skills/second-brain/SKILL.md · 172 lines

How it starts

The opening of the file, as written. The whole thing — 172 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/second-brain — Karpathy LLM Wiki workflow

Wraps an existing Second Brain in Obsidian (or any markdown-based vault). The wiki vault's CLAUDE.md is the authoritative schema — the skill orchestrates the operations the user has been doing manually.

Mental model

Three layers, each with a clear role:

raw/      →  wiki/         →  outputs/
sources      compiled         generated
                              artifacts
  • raw/ — unprocessed source material. Articles, highlights, ideas, braindumps, tweets. Type-prefixed (article-, idea-, highlights-, braindump-, note-, resource-, tweet-). Never deleted — source of truth.
  • wiki/ — AI-compiled topic pages. One page per concept, not per source. Interlinked via [[wikilinks]]. INDEX.md at root.
  • outputs/ — generated artifacts from queries: research summaries, analyses, slide decks. Named descriptively.

Folders to leave alone during wiki ops: Projects/, Daily/, Templates/, Inbox/, Notes/, Tasks.md, Kanban.md, Home.md.

Step 1 — Load vault config + schema

  1. Read references/vault-config.md for the vault path (default: ${SECOND_BRAIN_VAULT:-$HOME/Documents/SecondBrain}/)
  2. Read <vault>/CLAUDE.md for the authoritative schema. If present, trust it over references/schema.md — the user's vault is the source of truth.
  3. If no <vault>/CLAUDE.md, fall back to references/schema.md.

Step 2 — Parse mode

Invocation Mode
/sb capture / /second-brain capture / "capture this" / "save this to my brain" capture
/sb compile / "compile the wiki" / "process raw notes" compile
/sb query <question> / "ask my brain X" / "what does my brain say about Y" query
/sb lint / "lint the wiki" / "health check my brain" lint
/sb connect / "find connections" / "suggest wikilinks" connect
/sb search <term> / "search my notes for X" search

Step 3 — Run the mode

capture

Inputs: URL, pasted text, file path, or screenshot.

Read the full file on GitHub · 172 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 172 lines · 238 tokens per session scan A 1a76730e1be3

Subscribe to this mod's changes

second-brain is a skill published in the GitHub repository coreyhaines31/makerskills (778 stars, last pushed 2d ago), licensed MIT. It adds 238 tokens to every session and 2,884 once invoked, about $0.0012 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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