AI agents use create_subsurface to create or update resources in Openstudio — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Openstudio environment.
The tool creates new model entities (subsurfaces) which modifies the building energy simulation model reversibly. This is a Write action rather than Destructive (no deletion), Execute (no arbitrary code execution), or Financial. Medium severity because misuse could corrupt energy models, but changes are typically reversible through model editing.
From the tool's definition Tool name 'create_subsurface' indicates creation of a subsurface (window, door, etc.) in a building energy model, consistent with sibling tools like 'add_air_loop' and 'add_baseline_system' that create/modify model components.
Documented attack patterns abuse exactly the kind of access create_subsurface gives an agent:
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 create_subsurface:
{
"version": "1",
"default": "deny",
"tools": {
"create_subsurface": {
"limits": [
{
"counter": "create_subsurface_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_subsurface stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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create_subsurface. It is categorised as a Write tool in the Openstudio MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Openstudio MCP server in PolicyLayer and add a rule for create_subsurface: 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.
create_subsurface is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the create_subsurface 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.
Set action: deny in the PolicyLayer policy for create_subsurface. 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.
create_subsurface 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.
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.