Obsidian Guard

PyPI version Python 3.11+ License: MIT Tests

An MCP server for agent-safe Obsidian vault access. Provides read/write file tools with lint validation to prevent agents from writing malformed Obsidian markdown.

Why this exists

Most Obsidian MCP servers give agents direct write access with no markdown validation. Those that route through the Obsidian REST API gain some input sanitisation, but none validate content against Obsidian's markdown rendering rules before writing. obsidian-mcp-guard fills this gap: all writes are validated against Obsidian's markdown rules before they touch the vault, and if the content would render incorrectly, the write is rejected with a structured error explaining exactly which rule was violated. Writes can also be constrained to a single configurable vault path, giving agents a designated space to create and manage content on behalf of the user while preventing accidental or runaway writes to other vaults on the same filesystem. Directory traversal attacks are blocked at the path resolution layer, so a misconfigured, misbehaving, or prompt-injected agent cannot escape the write vault by constructing paths like Claude/../OtherVault/note.md

Features

• Read/list/create/update/delete/move notes via HOST_VAULT_PATH on the host filesystem
• Lint validation on all writes using mdlint-obsidian — blocks writes that violate Obsidian markdown rules (unclosed wikilinks, raw HTML, standard-markdown links, etc.)
• Write-vault isolation — writes are constrained to a single configurable vault; directory-traversal attacks are blocked on both read and write paths
• Composable — create_vault_server() returns a FastMCP instance that can be mounted into a larger server via import_server()
• Pre-validation tool — lint_note lets agents check content before committing a write

Installation

pip install obsidian-mcp-guard

For Claude Desktop users who don't want a manual install, uvx runs it directly with no setup:

uvx obsidian-mcp-guard

For local development:

python -m venv .venv
source .venv/bin/activate
pip install -e .

Configuration

Example layout expected under HOST_VAULT_PATH:

/path/to/your/vaults/
    Claude/      ← write operations land here
    Work/        ← readable but not writable
    Personal/    ← readable but not writable

Usage

As a standalone stdio server

# via the installed CLI entry point
HOST_VAULT_PATH=/path/to/your/vaults obsidian-mcp-guard

# or via python -m
HOST_VAULT_PATH=/path/to/your/vaults python -m obsidian_mcp_guard

Claude Desktop / Cursor config

{
  "mcpServers": {
    "obsidian": {
      "command": "uvx",
      "args": ["obsidian-mcp-guard"],
      "env": {
        "HOST_VAULT_PATH": "/path/to/your/vaults",
        "WRITE_VAULT": "Claude"
      }
    }
  }
}

Claude Code

claude mcp add obsidian -- uvx obsidian-mcp-guard

Pass environment variables with -e:

claude mcp add obsidian -e HOST_VAULT_PATH=/path/to/your/vaults -e WRITE_VAULT=Claude -- uvx obsidian-mcp-guard

Mounted into another FastMCP server

from contextlib import asynccontextmanager
from fastmcp import FastMCP
from obsidian_mcp_guard import create_vault_server

@asynccontextmanager
async def lifespan(app):
    await app.import_server(create_vault_server(
        vault_path="/path/to/your/vaults",
        write_vault="Claude"
    ))
    yield

mcp = FastMCP("my-agent", lifespan=lifespan)

@mcp.tool()
def search_notes(...):
    ...

Tools

Development

make install   # install package + test dependencies
make test      # run tests with coverage (90% minimum)
make build     # build source and wheel distributions
make clean     # remove build artefacts and cache files

See CONTRIBUTING.md for full guidelines.

Related projects

• mdlint-obsidian — the lint engine used to validate markdown against Obsidian's rendering rules