Low Risk

list_materials

list_materials

How to control list_materials ↓

What list_materials does on Openstudio

AI agents call list_materials 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_materials needs a policy

Despite the empty description (which slightly reduces confidence), the naming convention 'list_materials' strongly indicates this tool retrieves or enumerates materials from an OpenStudio model without modifying, deleting, or executing external operations. In the context of a building energy simulation tool, listing available materials is a safe, informational query.

From the tool's definition Tool name 'list_materials' indicates a retrieval operation. Server context shows this is for querying OpenStudio building energy simulation models. The 'list_' prefix is a strong signal of a read-only query operation with no side effects.

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

How to control list_materials

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_materials:

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

list_materials 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_materials

What does the list_materials tool do? +

list_materials. 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_materials? +

Register the Openstudio MCP server in PolicyLayer and add a rule for list_materials: 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_materials? +

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

Can I rate-limit list_materials? +

Yes. Add a rate_limit block to the list_materials 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_materials completely? +

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

list_materials 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.

Free to start. No card required.

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

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