flake-show

THE RISK

Low Risk

Why flake-show needs a policy

This tool reads and displays the structure of Nix flake outputs without modifying, executing external operations, or deleting data. It is purely informational, similar to 'list' or 'show' commands. The JSON output format confirms it is designed for data retrieval only.

From the tool's definition Tool name 'flake-show' and description 'Shows the outputs of a Nix flake as a structured tree' indicates a query/retrieval operation with '--json for machine-parseable output'.

Documented attack patterns abuse exactly the kind of access flake-show gives an agent:

POLICY

How to control flake-show

PolicyLayer is an MCP gateway — it sits between your AI agents and Make, and nothing reaches the server without passing your rules. This is the rule we recommend for flake-show:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "flake-show": {}
  }
}

flake-show is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Make — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

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All 202 Make tools →

Read tools on other servers

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Go deeper

Roll out MCP under one policy → Per-person scoped tokens, one central policy, and full audit across every server your team connects.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →
PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about flake-show

What does the flake-show tool do? +

Shows the outputs of a Nix flake as a structured tree. Uses --json for machine-parseable output by default. It is categorised as a Read tool in the Make MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on flake-show? +

Register the Make MCP server in PolicyLayer and add a rule for flake-show: 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 Make. Nothing to install.

What risk level is flake-show? +

flake-show is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit flake-show? +

Yes. Add a rate_limit block to the flake-show 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 flake-show completely? +

Set action: deny in the PolicyLayer policy for flake-show. 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 flake-show? +

flake-show is provided by the Make MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Make tool call.

Start from Make, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →