Obsidian + Claude Code as a second brain

Obsidian is widely used for note-taking, but recently it was discovered how to use it as a second brain

The main difference, as explored in The Future of Intelligence is a Network, lies in the shift from linear thinking to network thinking. The human brain doesn't operate in a linear way. It's a network of constant connections, where ideas from different domains collide to generate unprecedented insights.

This system I'll describe here is not just a way to "better organize your notes." It's a practical infrastructure for operating at the highest level of thinking: Network Thinking. While most productivity tools were designed for the industrial world — folders, hierarchies, sequences — Obsidian + AI creates an environment where your ideas can "have sex" (as Matt Ridley puts it) and generate offspring you would never imagine alone.

Imagine this scenario: you've been working on a complex project for months. Suddenly, when asking your AI to connect sparse points from your notes, it realizes that two apparently different client problems have the same root cause — a perception that would have taken months to emerge naturally. This is a second brain in action.

Second Brain

It's a term used very frequently, but most people who use it refer to something vague like an 'upgrade' of a note-taking system.

A true second brain does three things that a note-taking app can't.

1. Captures everything without friction, so nothing important is lost.
2. It connects information from different areas of your life and work, making patterns emerge that you would never find manually.
3. Helps you think actively, instead of just storing what you already thought.

Practical example of pattern #2: You note a frustration with a client about communication in March. In June, you register an insight about balanced leadership. In October, when asking for connections, your AI reveals that both point to the same principle: radical transparency. Without this connection, each note would remain isolated.

Obsidian handles the first two exceptionally well. Claude (or any other CLI tool like Codex, OpenCode) takes care of the third. Together, they create something that really feels like a system that amplifies your cognitive capacity, rather than just organizing your files.

Step 1: Preparation

Before connecting Claude to anything, you need a structured Obsidian vault. Most people create hundreds of folders and spend more time organizing notes than actually using them. The structure that really works must be as simple as possible.

It is very simple to be happy, but it is very difficult to be simple.

Currently I only have THREE MAIN FOLDERS

• Personal
• Knowledge Base
• Ideas

And as a complement, you can create a folder for work, or in my case articles.

Personal: In general, as the name says, here there are only personal notes. I put things related to work in terms of career progression, resume, brag doc, certifications, etc.

Knowledge Base: This folder is where the active work happens. Each concept receives its own note, which contains links to other notes, resources and relevant tasks related to it.

Concept note example:

# Radical Transparency

Leadership concept that emphasizes open and honest communication.

## Related links
- [[Client Communication]]
- [[Balanced Leadership]]

## Resources
- Article: "The Case for Radical Transparency"
- Book: "The Power of Transparency"

## Tasks
- [ ] Apply in weekly meetings
- [ ] Document learnings

Ideas: This is the inbox where everything ends up as soon as it arrives. Articles you want to read. Ideas that came up. Transcriptions of voice recordings. Book quotes. Everything arrives first in the ideas folder, without any difficulty or filter.

Articles/Projects: This is where the applications of the knowledge base will be.

Flow between folders: The general rule is simple: everything is born in Ideas, the relevant migrates to Knowledge Base, and the mature becomes Article/Project. Weekly, set aside 20 minutes for triage: what should be archived, what deserves to be developed, what can be discarded.

Basically that's it. Everything has its place. Nothing is lost in a complex hierarchy that takes more time to maintain than it saves.

Step 2: Create the habit of daily capture

The effectiveness of a knowledge management system lies not only in the tool, but in the discipline of capture. To avoid losing valuable insights, it's essential to have Obsidian installed on your phone and synced to your main vault.

The goal is to reduce friction:

• Sudden ideas: Record them in seconds while you're on the go.
• Readings: Transfer key concepts directly to your ideas folder.
• Dialogues: Note crucial points immediately after productive conversations.

By using the synchronized mobile app, you eliminate the barrier between thinking and recording. Saw something interesting? Copy to the ideas folder. Had an insight during a coffee? Note it in less than 30 seconds. This constant flow transforms your phone into a raw material capture network, feeding your system so that no useful information is lost in forgetting.

Annotation model

Creating automatic templates is the best way to consolidate the writing habit. Using a plugin like Templater, you ensure that each note starts with the correct structure (dates, tags and sections) without manual effort.

Alternatives: If you prefer not to use complex plugins, Obsidian's native "Templates" plugin or even text snippets from your editor already solve the problem. What matters is consistency, not the tool.

Concrete example of Daily Note:

# 2026-04-14

## Priorities of the day
- [x] Finish review of the article about Obsidian
- [ ] Meeting with product team at 3pm
- [ ] Process notes from last week

## Processing
- Idea about [[Second Brain]] → develop into permanent note
- Link about [[Radical Transparency]] → archive in Knowledge Base

## Project Log
**Obsidian Article:** The workflow section needs more concrete examples. Consider adding real cases.

## Insights
Consistency beats perfection. Even 5 minutes daily generate more value than a monthly session of hours.

This practice transforms sparse notes into a continuous and searchable record, serving as the glue that unites all your projects and ideas.

Step 3: Connect to Claude Code

Your Second Brain comes to life when connected to an AI that understands your context.

Level 1: Context Curation The manual method is the base. When starting a difficult task, select the relevant notes and provide them as initial context to Claude. The difference in output between an "empty" Claude and a Claude fed with your vault is brutal. Use it to expand your vision and find connections invisible to the naked eye.

Real interaction example:

You: I'm analyzing why my client X is dissatisfied with communication.

Empty Claude: "Consider having more frequent meetings and using tools like Slack..."

Claude with context (your notes about Radical Transparency + previous dissatisfactions + leadership insights):
"I see that you've documented similar patterns with other clients. Your notes suggest that the problem isn't frequency, but lack of transparency about challenges. You noted in March that 'clients value bad news early over good news late' - perhaps you should test radical transparency here?"

Level 2: The Vault as Development Environment Using Claude Code, you give the AI direct access to your vault's file system. This transforms Claude into an agent that can search, edit and organize your notes in real time.

To orchestrate this interaction, the CLAUDE.md file is indispensable. It works as your vault's System Prompt, defining:

• Structure: How notes are organized.
• Conventions: Tags, internal links and writing style.
• Objectives: What are the current priorities.

# My Obsidian Vault - Context for Claude

## Vault Structure
- /Ideas - Unprocessed captures
- /Knowledge Base - Processed permanent notes
- /Articles - Active project workspaces
- /Personal - Personal documents and career

## Active Projects
[List your 3-5 most active projects here]

## My Annotation Conventions
- Use [[double brackets]] for internal links
- Tag with #topic for easy filtering
- Daily notes in YYYY-MM-DD format
- I separate concepts (Knowledge Base) from applications (Articles)

## How I Want Claude to Help Me
- Connect ideas between notes that I may have missed
- Question my reasoning when something doesn't hold up
- Help transform raw captures into permanent notes
- Bring up relevant notes when I'm working on a specific problem
- Identify patterns between seemingly disconnected ideas

Step 4: Workflows

After your vault is configured and connected to Claude, here are the specific workflows that generate the most value.

Idea Development

When you have an initial idea in your inbox that you want to develop into a permanent note, paste it into Claude along with any related notes from your file.

Execute this command:

Here's a general idea I noted: [PASTE THE IDEA]. Here are the related notes I already have: [PASTE THE RELEVANT NOTES]. Help me develop this into a complete and permanent note. What is the main idea? What are the implications? What questions does this raise? What would make this idea stronger or weaker?

Expected result: Claude will identify the core of the idea, propose implications you haven't considered, point out gaps in reasoning, and suggest connections with other notes in your vault.

Connection Identifier

One of the most valuable things a second brain can do is reveal non-obvious connections between ideas that reside in different parts of your "mental vault".

Once a week, paste a selection of notes from different areas of your vault into Claude and execute this command:

Here are notes from different areas of my work: [PASTE THE NOTES]. What non-obvious connections do you see between these ideas? Are there patterns I may have missed? Is there any contradiction between my thinking in different areas that I should resolve?

Expected result: The AI will identify themes that cross multiple areas, point out contradictions in your thinking that you didn't notice, and reveal how ideas from different projects can feed each other. This is the workflow that most fulfills the promise of the "second brain" - last week, I threw 3 months of notes into Claude and it found a pattern I completely ignored: two different client problems with exactly the same root cause.

Writer

When you need to write something substantial, be it a long article, a report or an in-depth analysis, start by gathering all the relevant notes on the subject you already have.

Paste them into Claude and execute this command:

Here are all the notes I've accumulated about [TOPIC]: [PASTE NOTES]. I need to write a [FORMAT] of approximately [LENGTH] targeted at [AUDIENCE]. First, help me identify the most important ideas from these notes. Then, help me structure them into a logical outline. Finally, help me identify what's missing to make this text significantly stronger.

Expected result: Claude will synthesize your scattered notes into a coherent structure, identify gaps you need to fill, and provide an outline ready for you to start writing. What used to take hours of preparation now takes twenty minutes — you just need to execute.

Step 5: Mind Map

Obsidian's graph visualization is not an ornament; it's a map of your consciousness. To use it with intention, filter it by projects. You'll immediately see where your ideas are flourishing and where they are stagnant. "Isolated notes" are not flaws, they are invitations to explore new connections.

Practical usage example: When filtering the graph by the "Articles" project, you notice that three notes about productivity are isolated from the rest. This may indicate:

• A missed opportunity to connect concepts
• That these notes need to be developed
• Or that they deserve to be archived if they are no longer relevant

Use the graph weekly as a visual diagnostic tool: very dense areas may need organization; very sparse areas may need development.

What This System Really Builds

Uniting Obsidian and Claude is not just for "storing things". It serves to amplify your creative surface area.

1. Refined Reasoning: With Claude accessing your history, your thinking is challenged and refined at a speed impossible to achieve alone.
2. Temporal Perspective: When reviewing your daily notes months later, you identify intellectual patterns that would be invisible in the chaos of day-to-day.

Verdict

The difference between a revolutionary system and a note cemetery is a single word: consistency.

Don't try to be perfect; be present. Ten minutes of curation per day transform, in a few months, into an incalculable intellectual advantage. Those who build and maintain this habit start to think more clearly and create more easily. Those who give up are left with just pretty folders.

What to expect after 3 months of consistency:

• 100+ notes in the Knowledge Base connected organically
• 5-10 insights significant that would not have emerged without the system
• 50% reduction in preparation time for writing or complex projects
• Reliable external memory — you never lose an important idea again

First, create the habit. Then let the system optimize you.

Bonus: Automate everything

This article describes the manual approach to transforming your Obsidian into a second brain. But there is a way to automate practically everything described here.

Obsidian Second Brain is a skill for Claude Code that transforms your vault into an intelligent and autonomous partner. Instead of you being the janitor organizing notes, Claude takes care of memory while you focus on thinking.