Low Risk

list_output_variables

List available output variables and meters from a completed simulation.

How to control list_output_variables ↓

What list_output_variables does on Openstudio

AI agents call list_output_variables to retrieve information from Openstudio without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

Low Risk

Why list_output_variables needs a policy

This tool retrieves metadata and results from a completed simulation. It performs a passive query operation with no capability to modify models, delete data, execute arbitrary code, or trigger financial transactions. The blast radius of misuse is minimal—an AI agent could only access information that already exists.

From the tool's definition Tool name 'list_output_variables' and description 'List available output variables and meters from a completed simulation' indicate querying/retrieving data from existing simulation results with no modifications or side effects.

Documented attack patterns abuse exactly the kind of access list_output_variables gives an agent:

How to control list_output_variables

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

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_output_variables": {}
  }
}

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

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

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Questions about list_output_variables

What does the list_output_variables tool do? +

List available output variables and meters from a completed simulation. It is categorised as a Read tool in the Openstudio MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_output_variables? +

Register the Openstudio MCP server in PolicyLayer and add a rule for list_output_variables: 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 Openstudio. Nothing to install.

What risk level is list_output_variables? +

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

Can I rate-limit list_output_variables? +

Yes. Add a rate_limit block to the list_output_variables 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 list_output_variables completely? +

Set action: deny in the PolicyLayer policy for list_output_variables. 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 list_output_variables? +

list_output_variables is provided by the Openstudio MCP server (natlabrockies/openstudio-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Openstudio tool call.

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

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146 Openstudio tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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