neo4j-guard

neo4j-guard is a Python library that blocks dangerous Cypher queries before execution. It wraps the official neo4j driver and parses every query with Neo4j's own Cypher 25 grammar.

Features

• Configurable read and write modes
• Dangerous queries blocked by default
• Error messages an agent can act on

Requirements

• Python 3.10+
• neo4j 5.8+

Installation

pip install neo4j-guard

Use with Neo4j driver

from neo4j import GraphDatabase
from neo4j_guard import GuardError, guard

driver = guard(GraphDatabase.driver(URL, auth=AUTH))
try:
    driver.execute_query("CREATE (:Person {name: 'Ada'})")
except GuardError as error:
    print(error)  # CREATE is not allowed in read mode

Use with LangChain

from langchain_neo4j import Neo4jGraph
from neo4j_guard import guard

graph = Neo4jGraph(url=URL, username=USERNAME, password=PASSWORD)
guard(graph._driver)

Use with Neo4j MCP server

import asyncio
from mcp_neo4j_cypher.server import create_mcp_server
from neo4j import AsyncGraphDatabase
from neo4j_guard import guard


async def main() -> None:
    driver = guard(
        AsyncGraphDatabase.driver(URL, auth=AUTH),
        allow=["apoc.meta.schema"],
    )
    await create_mcp_server(driver, read_only=True).run_stdio_async()


asyncio.run(main())

Configuration

neo4j-guard is configurable. By default, a guarded driver can only run a small set of read-only Cypher.

guard(
    driver,
    mode="write",  # "read" (default) or "write"
    allow=["DELETE", "apoc.load.json"],
    disallow=["apoc.meta.*", "Employee", "Person.ssn"],
)