AI agents use create_surface 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 data structures (surfaces) within an energy simulation model, which is reversible and represents a Write operation. Severity is medium because unauthorized surface creation could corrupt or mislead a building energy model, affecting design decisions, but effects remain within the simulation domain and are modifiable.
From the tool's definition Tool name 'create_surface' indicates creation of a geometric or simulation surface in an OpenStudio energy model.
Documented attack patterns abuse exactly the kind of access create_surface 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_surface:
{
"version": "1",
"default": "deny",
"tools": {
"create_surface": {
"limits": [
{
"counter": "create_surface_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_surface 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_surface. 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_surface: 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_surface 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_surface 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_surface. 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_surface 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.