nb-mcp-server

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, delete, move, list, search, todo, do, undo, tasks, bookmark, folders, mkdir, import, status, notebooks, plus the body-aware tools replace_note_body, edit_note_substring, edit_note_lines, retitle_note, edit_note_tags, and the line tools show_note_lines, search_note_lines. These bypass the multiplexed command dispatch. The multiplexed nb tool remains as the compact/backcompat compatibility surface for the retained commands.

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:

Body-Aware Editing

The legacy nb.edit tool (and its overwrite/append/prepend modes) was removed in the nb-api 0.3 cutover. The body-aware replacement tools are direct-only (no multiplexed nb.* aliases) and are designed to prevent the destructive whole-note-overwrite failure mode that the old surface enabled:

• replace_note_body — replace the entire note body with plain UTF-8 new_body. Requires the body fingerprint from a preceding show; a stale fingerprint is rejected with re-read guidance so you cannot overwrite a note you have not just read.
• edit_note_substring — replace one or more occurrences of a plain-text pattern with replacement. expected_count must match the actual match count; an optional fingerprint guards against stale edits.
• edit_note_lines — apply a batch of disjoint insert/delete/replace edits verified against line anchors from one original snapshot; content is bare text (no terminator bytes; the library appends the document EOL, so single-line replaces never merge the next line).
• retitle_note — change the title without changing the path.
• edit_note_tags — add and/or remove tags in one atomic operation.

These tools address notes by a flat id (alias selector) string exactly like show/delete/move; notebook-relative filenames are not exposed, and qualified selectors returned by show/show_note_lines/ search_note_lines round-trip directly as id. Since nb-api 0.4, numeric .index ids are surfaced too: reads and mutation outcomes carry selector plus numeric_id, and <folder>/<id> / <id> are accepted as id (ids are folder-local, positional, and never reused; path stays canonical). Body content (pattern, replacement, title, new_body, line-edit content) and line/search text/title are native UTF-8 strings with no base64 anywhere on the wire. Line-level reads are available through show_note_lines (bounded, anchored windows with a document-level eol declaration — lf/crlf plus has_final_eol — instead of per-line terminators) and search_note_lines (anchored matches, no EOL fields by design), which support search-to-edit without reading the whole note. New notes get nb-faithful filenames mangled from the title (Hello World Title → hello_world_title.md).

add creates notes only: todo-shaped content (checkbox lines or a Tasks heading outside fenced code blocks) is rejected with a hint to use the todo tool instead.

Invoking multiplexed nb.edit is rejected with recovery guidance naming the replacement tools. The body-aware and line tools are direct-only: invoking them through the multiplexed nb tool is rejected.

Structured Results

• show returns a text-first slim structured envelope: selector, path, kind, todo_state, title (normalized Option<String>), tags, body (full UTF-8 text), body_contiguous, fingerprint, and numeric_id. No base64 field is exposed. When the source is not valid UTF-8, show returns a typed NonUtf8 error carrying the MIME hint plus guidance to an external raw-retrieval facility outside MCP (the nb CLI); a non-textual target returns UnsupportedShowTarget. Neither ever returns base64 bytes.
• Mutating tools (add, todo, bookmark, mkdir, delete, move, do, undo, and the body-aware tools) return a structured CommitOutcome: commit_created, revision_id, pre_revision, and per-operation path/selector/numeric_id/noop/fingerprint. Idempotent no-op mutations report commit_created: false.

Typed Error Surfaces

nb-api 0.4 introduces typed failures that the MCP layer translates into actionable diagnostics on both the multiplexed nb.* surface and the first-class tool surface. NonUtf8 and IndexLockTimeout (busy .index lock; retry later, nothing mutated) join the existing set:

• 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.
• Stale-editing guards: FingerprintMismatch, AnchorMismatch, and OccurrenceMismatch tell the caller to re-read the note and retry with fresh fingerprint/anchors/counts.
• FragmentedBody: a multi-fragment body (for example a bookmark with multiple body fragments) refuses line/substring/body-replace operations; metadata operations (retitle_note, edit_note_tags) still apply.
• DirtyBaseline: a mutation refuses when the notebook worktree/index is dirty; the diagnostic tells the caller to commit or clean it first.
• IndeterminateCommit / RecoveryRequired: commit completion is unknown or recovery is needed; the diagnostic instructs the caller not to auto-retry and to inspect HEAD/status before acting.
• GateTimeout: the notebook is busy; retry later.
• PathCollision / PathIgnored / UnsupportedStructure / PlanValidation: surface the specific path/plan guidance.

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 body-aware editing surface, typed errors, structured results, and sanitized empty listings all come from nb-api 0.4.

Contributing

See the contribution guide and code of conduct:

• Contribution guide
• Code of conduct

License

Apache 2.0