Wren MCP server

A small companion app that lets Claude search, read, write and organise your Wren notes - running entirely on your own computer.

Short version: install it in Claude Desktop, point it at your Wren notes folder, and you can ask Claude things like "what are my open todos?" or "make a note that says call the vendor Tuesday." Your notes never leave your computer.

What it does

Once installed, Claude Desktop can work with your actual notes - no copy-pasting. The server exposes eleven tools. Four of them read:

Search your notes by text, tag, or due date.
Read a specific note in full.
List your notes, a page at a time.
Get the index - the whole catalog at once.

The other seven write. Claude can change your notes, so it is worth knowing exactly what it can do:

Create a new note. By default it goes to a staging area (_inbox) for you to review in Wren before it joins your main notes.
Update an existing note's body, title, or due date.
Append text to the end of a note.
Set tags on a note, adding or removing them.
Delete a note - a soft delete, described below.
Promote a staged _inbox note into your main notes.
Restore a note that was soft-deleted.

What keeps the writes safe

The write tools are not a free hand over your notes folder. Five things constrain them:

It has to read a note before it can change it. Reading returns a fingerprint of the note's contents, and every edit has to hand that fingerprint back. If the note changed on disk in between - you edited it in Wren, or Drive synced a newer copy - the edit is rejected as a conflict instead of overwriting your version. There is no blind overwrite path.
Edits can be previewed. Every edit tool takes a dry-run flag that returns the exact diff without touching the file, so Claude can show you a change before making it.
Deleting is a soft delete. A deleted note is moved into a .trash folder inside your notes folder, never actually erased, and a restore tool moves it back. Deleting also requires an explicit confirmation flag, as does promoting a staged note into your main notes.
It cannot reach outside your notes folder. Every path is resolved and checked against the folder you chose; attempts to escape it are rejected.
AI edits are labelled. Notes that Claude creates or edits get created_by, last_edited_by and last_edited stamped into their frontmatter, so an AI-written note is always distinguishable from one you wrote.

Full technical detail, including the write-safety model, is in the wren-mcp README.

Your notes stay on your computer

The Wren MCP server is a local program. It reads the notes folder you point it at, on your own disk, and hands results to Claude over a local connection on your machine. It has no server of its own, requires no Wren account or login, and uploads nothing. The only data that leaves your computer is whatever you choose to share with Claude in a conversation — the same as any normal Claude chat. Full details in the Wren privacy policy.

Requirements

The Claude Desktop app (macOS or Windows). Local extensions like this run in Claude Desktop only — not the web or mobile apps.
A Wren notes folder on your computer (the folder you chose in Wren). If you use Wren's Google Drive backend with Drive for Desktop in mirror mode, point it at that synced folder.

Install

Download Wren.mcpb.
Open Claude Desktop → Settings → Extensions.
Drag Wren.mcpb into the Extensions area (or use the install control).
When prompted, set the notes folder to your Wren notes folder.
Click Install, then make sure the Wren extension is enabled in a new chat.

To confirm it works: in a Claude Desktop chat, say "make a note that says MCP test," then open Wren and look in the Inbox — your new note will be there to keep or discard.

FAQ

Which Claude apps can I use it with?

Claude Desktop (macOS / Windows) only. Local extensions can't run in Claude.ai on the web, the mobile apps, or Cowork.

Can it change or delete my existing notes?

Yes, and you should know that before you install it. Claude can update a note's body or title, append to it, change its tags, and delete it. Deleting is a soft delete - the note moves to a .trash folder in your notes folder and can be restored - and it requires an explicit confirmation flag. Edits require Claude to read the note first and pass back a fingerprint of what it read, so a note that changed underneath it is a rejected conflict rather than a silent overwrite. See what keeps the writes safe above.

Can I stop it from changing anything?

Not with a server-side switch - the tools are always registered. What you control is the conversation: Claude asks before it edits, and you can tell it to stay read-only in a given chat. If you want a hard guarantee that nothing changes, don't install the extension, or keep a backup of your notes folder. It's plain Markdown files, so any backup tool works.

Does it need a login?

No login and no account. You point it at a folder — that's the whole setup.

Where do AI-created notes go?

Into a staging area (the _inbox folder). You review each one in Wren and decide whether to keep (promote) or discard it. They never silently join your main notes.

Why isn't it built into the Wren app or extension?

Browser extensions and web apps can't run this kind of local program — it has to be a separate small app. It just reads the same notes folder Wren writes to, so it's the same notes either way.