brain

brain is a skill for Claude Code, Codex from jzhao234/big-brain. It costs 87 tokens per session (536 once invoked), scanned A, original, MIT.

A guide for orienting an agent in the user's second brain: a personal vault of notes about projects, tasks, and ideas.

In plain words
What is it for?
Use it at the start of ongoing work, or when asking what is being worked on, what is overdue, what is due soon, or what tasks are open.
Why use it?
It gives the agent current context about active work, deadlines, inbox items, and project history instead of making it reconstruct that context from scratch.

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/jzhao234/big-brain/brain
Any agent
npx skills add jzhao234/big-brain --skill brain
Clone the repo
git clone --depth 1 https://github.com/jzhao234/big-brain

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 brain

README.md
[![agentmods](https://agentmods.dev/badge/skills/jzhao234/big-brain/brain.svg)](https://agentmods.dev/skills/jzhao234/big-brain/brain)
Your own site
<a href="https://agentmods.dev/skills/jzhao234/big-brain/brain"><img src="https://agentmods.dev/badge/skills/jzhao234/big-brain/brain.svg" alt="Measured on agentmods" height="20"></a>
Per session 87 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 536 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00087 $0.00536
Opus 5 $0.00044 $0.00268
Sonnet 5 $0.00017 $0.00107
Haiku 4.5 $0.00009 $0.00054

Measured 4d ago against content hash ae34bb3ff01f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

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 4d 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/brain/SKILL.md · 36 lines

What it actually says

brain

The big-brain vault is the user's external memory, shared by all their AI tools. This skill loads it and switches you into brain-aware mode. The vault is whichever one big-brain resolves — the BIG_BRAIN_VAULT env var, a --vault path, or the nearest brain.config.json. Use the big-brain CLI or the big-brain MCP tools; don't hardcode a vault path.

With no argument

  1. Run big-brain status (or call the brain_overview MCP tool).
  2. Report in one screen, BLUF: active projects with their next task, anything overdue or due this week, inbox count if it's piling up. No filler; skip empty sections.
  3. If the vault hasn't been linted recently, run big-brain doctor and surface only warnings.

With an argument

Treat it as a project or topic: big-brain show <arg> (falling back to big-brain search <arg>), then summarize where it stands — goal, status, open tasks, last Log entries — and ask what to work on.

Brain-aware mode (rest of the session)

From here on, keep the vault current as a side effect of the work:

  • Decisions, progress, and problems → big-brain daily --log "..." and a Log line on the affected project.
  • New commitments → project notes; new action items → big-brain task add.
  • Completed work → big-brain task done <id>.
  • Facts worth keeping with no obvious home → big-brain capture "...".

Do routine captures/logs without asking (mention them in one line); ask before rewriting or archiving existing notes. If the vault has git auto-commit enabled, these saves also commit and push on their own. At the end of a work session, make sure what happened is reflected in the vault — the next session (or another LLM) starts from there.

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. 4d ago First seen · 36 lines · 87 tokens per session scan A ae34bb3ff01f

Subscribe to this mod's changes

brain is a skill published in the GitHub repository jzhao234/big-brain (0 stars, last pushed 3d ago), licensed MIT. It adds 87 tokens to every session and 536 once invoked, about $0.0004 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 2026-08-31.

Related

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