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.
npx skills add coreyhaines31/makerskills --skill second-braingit clone --depth 1 https://github.com/coreyhaines31/makerskillsWrote 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.
[](https://agentmods.dev/skills/coreyhaines31/makerskills/second-brain)<a href="https://agentmods.dev/skills/coreyhaines31/makerskills/second-brain"><img src="https://agentmods.dev/badge/skills/coreyhaines31/makerskills/second-brain/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/coreyhaines31/makerskills/second-brain"><img src="https://agentmods.dev/badge/skills/coreyhaines31/makerskills/second-brain.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00240 | $0.02918 |
| Opus 5.5 | $0.00096 | $0.01167 |
| Sonnet 5.5 | $0.00048 | $0.00584 |
| Haiku 4.5 | $0.00024 | $0.00292 |
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 today.
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.
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 schema doc (CLAUDE.md or AGENTS.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.mdat 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
- Read
references/vault-config.mdfor the vault path (default:${SECOND_BRAIN_VAULT:-$HOME/Documents/SecondBrain}/) - Read the vault's schema doc —
<vault>/CLAUDE.mdor<vault>/AGENTS.md, whichever exists (if both, read both) — for the authoritative schema. If present, trust it overreferences/schema.md— the user's vault is the source of truth. - If neither exists, 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 |
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.
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.
- today Changed · +2 tokens per session 4074192a6a87
- 14d ago Changed 8fe514b4d2db
- 1mo ago First seen · 172 lines · 238 tokens per session scan A 1a76730e1be3
second-brain is a skill published in the GitHub repository coreyhaines31/makerskills (869 stars, last pushed today), licensed MIT. It adds 240 tokens to every session and 2,918 once invoked, about $0.0010 per session on Opus 5.5. 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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