nb-mcp

MCP server wrapping the nb CLI for LLM-friendly note-taking.

Motivation

Using nb directly via shell has two problems for LLM assistants:

1. Backtick escaping: Markdown content with backticks triggers shell command substitution, corrupting notes.

2. Notebook context: nb assumes a default notebook, making per-project use awkward.

This MCP server solves both by:

• Accepting content as JSON parameters (no shell escaping needed)
• Qualifying all commands with an explicit notebook

Quick Start

Prerequisites

Install nb by following the official instructions: nb installation guide.

Installation

From crates.io:

cargo install nb-mcp-server

See the changelog for release history and upgrade notes.

Or download a prebuilt binary from GitHub Releases.

Build from Source

cargo build --release

Run

With default notebook from environment:

NB_MCP_NOTEBOOK=myproject ./target/release/nb-mcp

Or via CLI argument (takes precedence):

./target/release/nb-mcp --notebook myproject

Disable commit and tag signing in the notebook repository:

./target/release/nb-mcp --notebook myproject --no-commit-signing

Allow new notes at the notebook root instead of requiring a folder:

./target/release/nb-mcp --notebook myproject --allow-top-level-notes

Print the installed version:

./target/release/nb-mcp --version

Show the resolved notebook path and state directory:

./target/release/nb-mcp --show-paths

MCP Configuration

Add to your MCP client configuration (e.g., .mcp.json):

{
  "mcpServers": {
    "nb": {
      "command": "/path/to/nb-mcp",
      "args": ["--notebook", "myproject"]
    }
  }
}

Commands

The canonical access path is the multiplexed nb tool with a command parameter, which reduces the token footprint of the MCP server. The args field must be a JSON object. Stringified JSON payloads are rejected. Unknown args fields are rejected instead of ignored; use the exact command schema fields or documented aliases. Returned identifiers such as coordination/mcp/1 or myproject:coordination/mcp/1 are nb selectors, not filesystem paths in the current repository. Notebook storage is managed by nb configuration. The notebook argument must be a bare notebook name. Use folder for folder paths and id / selector for note selectors. Existing-item commands accept copied selectors such as myproject:coordination/mcp/1, but reject conflicts with a separate notebook argument.

First-Class Tools

All commands are also available as direct first-class tools with typed schemas: add, show, edit, delete, move, list, search, todo, do, undo, tasks, bookmark, folders, mkdir, import, status, notebooks. These bypass the multiplexed command dispatch. The multiplexed nb tool remains as the compact/backcompat compatibility surface.

Notes

Todos

Organization

Examples

Create a note with code:

{
  "command": "nb.add",
  "args": {
    "title": "API Design Notes",
    "content": "# API Design\n\nUse `GET /items` for listing.\n\n```python\nresponse = client.get('/items')\n```",
    "tags": ["design", "api"],
    "folder": "docs"
  }
}

Search for notes:

{
  "command": "nb.search",
  "args": {
    "queries": ["API", "design"],
    "mode": "any",
    "tags": ["design"]
  }
}

Tagging Suggestions

For multi-LLM projects, consider using consistent tag prefixes (optional). Example categories and prefixes:

Edit Behavior

nb.edit requires an explicit mode value. The schema advertises overwrite, append, and prepend. overwrite replaces every byte of the note body (it is destructive). The legacy input value replace is still accepted through the upstream nb-api serde alias and is interpreted as overwrite.

Omitting mode is rejected before nb is invoked. Clients that relied on the destructive default must now send mode: "overwrite" explicitly.

Typed Error Surfaces

nb-api 0.2 introduces two typed failures that the MCP layer translates into actionable diagnostics on both the multiplexed nb.* surface and the first-class tool surface:

• show on a non-text selector (folder, archive, image, ...): the error names the selector and the actual non-text type, states that show reads text notes only, and points the caller at folders/list. The server never silently re-routes show to another command.
• add with both a title and a content whose first nonblank line is an H1 that duplicates the title: the error names the title and the detected heading and tells the caller to remove the duplicate H1 or omit the separate title.

Configuration

Notebook Resolution

Priority order:

1. Per-command notebook argument (highest)
2. CLI --notebook flag
3. NB_MCP_NOTEBOOK environment variable
4. Git-derived default from the master worktree path

If no notebook can be resolved, commands fail with a configuration error. The server does not fall back to nb's default notebook.

If the resolved notebook does not exist, the server creates it automatically. Use --no-create-notebook to disable automatic creation.

Logging

Logs are written to ~/.local/state/nb-mcp/{project}--{worktree}.log (XDG-compliant).

For Git worktrees, logs are named after both the master project and the worktree basename to avoid collisions between multiple MCP server instances.

Use --show-paths to print the resolved notebook path and state directory.

Folder Requirement

By default, note-creating commands require a folder argument so agents do not accidentally litter project notebook roots. This applies to nb.add, nb.todo, nb.bookmark, and nb.import. Use nb.mkdir to create new folders and nb.folders to list existing folders.

Set NB_MCP_ALLOW_TOP_LEVEL_NOTES=true or pass --allow-top-level-notes to permit root-level note creation.

Notebook Overrides

Mutating commands warn after successful writes when the notebook argument targets a notebook other than the project default. Cross-notebook writes remain allowed for collaboration across teams, but the warning helps catch accidental notebook/folder confusion.

The notebook argument accepts only bare notebook names, not selector syntax. For example, use notebook: "other-team" with folder: "todos/mcp", not notebook: "other-team:todos/mcp".

Control log level with RUST_LOG:

RUST_LOG=debug nb-mcp --notebook myproject

Commit Signing

Use --no-commit-signing to disable commit and tag signing in the notebook repository. The server updates the notebook repository's local Git config so signing prompts do not block MCP tool calls.

Related Projects

• nb-api — Typed Rust interface to the nb CLI. Published on crates.io. This MCP server depends on nb-api for all note-taking primitives; the edit vocabulary, typed show/add errors, and sanitized empty listings all come from nb-api 0.2.

Contributing

See the contribution guide and code of conduct:

• Contribution guide
• Code of conduct

License

Apache 2.0