gem-list

Lists installed Ruby gems with version information. Returns structured JSON with gem names and versions.

SERVERDocker SOURCE@paretools/docker

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-dave-london-docker/gem-list.md

WHAT IT DOES

What gem-list does on Docker

AI agents call gem-list to retrieve information from Docker without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why gem-list is rated Low

The gem-list tool performs a read-only query of the local Ruby environment to enumerate installed packages. It has no side effects, cannot modify system state, and presents minimal security risk. Even in an agentic context, misuse would only result in information disclosure about the Ruby installation, not operational harm.

From the tool's definition Tool description states 'Lists installed Ruby gems with version information. Returns structured JSON with gem names and versions.' This is a pure query operation that retrieves data without modification.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs gem-list safely

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

gem-list Allowed

gem-list is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "gem-list": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

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

FAQ

Questions about gem-list

What does the gem-list tool do? +

Lists installed Ruby gems with version information. Returns structured JSON with gem names and versions. It is categorised as a Read tool in the Docker MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on gem-list? +

Register the Docker MCP server in PolicyLayer and add a rule for gem-list: 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 Docker. Nothing to install.

What risk level is gem-list? +

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

Can I rate-limit gem-list? +

Yes. Add a rate_limit block to the gem-list 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 gem-list completely? +

Set action: deny in the PolicyLayer policy for gem-list. 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 gem-list? +

gem-list is provided by the Docker MCP server (@paretools/docker). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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