second-brain

second-brain is a skill for Claude Code, Codex from SurajGThakkar/agent-skills. It costs 80 tokens per session (873 once invoked), scanned A, original, MIT.

A workflow for building and maintaining a personal wiki, sometimes called a second brain: a connected collection of notes that stores and develops knowledge over time. It has separate paths for setting up, maintaining, and operating the wiki.

In plain words
What is it for?
Use it to start a personal wiki, import and break down source material, maintain its structure, check its health, and operate it through workspace instructions.
Why use it?
It gives raw information a lasting place instead of leaving it in scattered documents or one-off summaries. It also records links and detailed knowledge so the wiki can grow over time.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions CLAUDE.md; mentions AGENTS.md.

Good fit Use it to start a personal wiki, import and break down source material, maintain its structure, check its health, and operate it through workspace instructions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/surajgthakkar/agent-skills/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 SurajGThakkar/agent-skills --skill second-brain
Clone the repo
git clone --depth 1 https://github.com/SurajGThakkar/agent-skills

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 second-brain

README.md
[![agentmods](https://agentmods.dev/badge/skills/surajgthakkar/agent-skills/second-brain/github.svg)](https://agentmods.dev/skills/surajgthakkar/agent-skills/second-brain)
Your own site
<a href="https://agentmods.dev/skills/surajgthakkar/agent-skills/second-brain"><img src="https://agentmods.dev/badge/skills/surajgthakkar/agent-skills/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.

agentmods 80×15 button for second-brain

Your own site · 80×15
<a href="https://agentmods.dev/skills/surajgthakkar/agent-skills/second-brain"><img src="https://agentmods.dev/badge/skills/surajgthakkar/agent-skills/second-brain.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 80 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 873 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 $0.00080 $0.00873
Opus 5 $0.00040 $0.00436
Sonnet 5 $0.00016 $0.00175
Haiku 4.5 $0.00008 $0.00087

Measured 9d ago against content hash 42a618bdd172, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, 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 9d ago.

The scan reads SKILL.md. This mod also ships 8 executable files (scripts/build_index.py, scripts/calibrate_confidence.py, scripts/common.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/knowledge-management/second-brain/SKILL.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Second Brain

Bootstrap, maintain, or operate an LLM-managed personal wiki using the LLM Wiki at Scale pattern. The LLM incrementally builds a persistent, interlinked wiki from raw sources — knowledge compiled once, kept current, compounding with every ingest.

Three branches. Read the disclosed file before executing.


Shared Rules

  • TaskCreate visible. Use TaskCreate to make stages visible to the user on every branch.
  • Scripts propose, LLM disposes. Deterministic scripts hand clean worklists; the LLM exercises judgment. Never blind-apply script output.
  • Anti-bleed rule. "Lean" applies ONLY to operational files (AGENTS.md, playbooks, scripts). Content generation — ingestion, entity extraction, concept pages — must be relentless: sprawling, exhaustive, granular. A rich source spawns 10-15 pages. If you produce one summary page, you are committing premature completion and stranding knowledge. The schema is lean so the content can be massive.
  • Handoff. Day-to-day ingest and query run through the vault's own AGENTS.md (or CLAUDE.md) playbooks once live — not this skill.

Branch: Setup

When: User wants a new vault, or to continue a partial bootstrap. Read: references/setup.md Completion: Every phase (Discovery → Scaffold → Interview → Inject → Build → Orient) completed. Zero {...} placeholders remaining in generated files. User oriented with core commands and a suggested first action.


Branch: Maintain

When: User asks to lint, health-check, rebuild index, rotate logs, calibrate confidence, or normalize tags. Read: references/maintenance.md Completion: Lint loop exits with zero criticals. Index rebuilt. Log entry appended. Every worklist item accepted, modified, or declined by the user.


Branch: Operate

When: User wants to build or schedule an autonomous wiki-maintenance Operator. Read: references/operator.md Completion: Operator prompt saved with zero {{...}} placeholders. Schedule wired via the schedule skill. User told the cadence and how to manage the trigger. Scope: Pure wiki upkeep, scheduled and unattended — lint, the three safe fixers, index rebuild, log rotation, source-queue and scratch visibility — run locally against the vault with no external connectors and no MCP. It never resolves judgment calls (broken links, contradictions, tag drift) and never auto-ingests; both stay queued for a supervised session. Optionally researches open questions into raw/scratch/ for later review — never into wiki/, and off by default.

Read the full file on GitHub · 67 lines

Files

What ships with it

41 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. 9d ago First seen · 67 lines · 80 tokens per session scan A 42a618bdd172

Subscribe to this mod's changes

second-brain is a skill published in the GitHub repository SurajGThakkar/agent-skills (2 stars, last pushed 1mo ago), licensed MIT. It adds 80 tokens to every session and 873 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.

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