run_cypher

Execute Cypher query on Neo4j database

SERVERNcp SOURCE@portel/ncp

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-portel-dev-ncp/run-cypher.md

WHAT IT DOES

What run_cypher does on Ncp

AI agents invoke run_cypher to trigger actions in Ncp. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

RISK

Why run_cypher is rated High

This tool executes code (Cypher queries) against a Neo4j database. While Cypher queries can be read-only, the tool permits arbitrary query execution, which includes the ability to modify or delete data depending on database permissions and query content.

From the tool's definition Tool name 'run_cypher' and description 'Execute Cypher query on Neo4j database' explicitly indicate execution of arbitrary database queries.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs run_cypher safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Ncp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For run_cypher, this is the rule to start with:

run_cypher Rate-limited

run_cypher stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "run_cypher": {
      "limits": [
        {
          "counter": "run_cypher_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Ncp, apply this rule, and every run_cypher call is checked against it from then on.

FAQ

Questions about run_cypher

What does the run_cypher tool do? +

Execute Cypher query on Neo4j database. It is categorised as a Execute tool in the Ncp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on run_cypher? +

Register the Ncp MCP server in PolicyLayer and add a rule for run_cypher: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Ncp. Nothing to install.

What risk level is run_cypher? +

run_cypher is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit run_cypher? +

Yes. Add a rate_limit block to the run_cypher rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block run_cypher completely? +

Set action: deny in the PolicyLayer policy for run_cypher. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides run_cypher? +

run_cypher is provided by the Ncp MCP server (@portel/ncp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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