AI agents use replace_zone_terminal 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 modifies model data (zone terminal units in an HVAC system) in a reversible manner typical of Write operations. While not destructive (the old terminal can theoretically be re-created), it alters building simulation parameters that directly affect energy model results and potentially building design outputs.
From the tool's definition Tool name 'replace_zone_terminal' indicates modification of HVAC terminal unit equipment in building energy models. The action replaces (modifies) existing simulation model components. Description is empty, limiting confidence.
Documented attack patterns abuse exactly the kind of access replace_zone_terminal 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 replace_zone_terminal:
{
"version": "1",
"default": "deny",
"tools": {
"replace_zone_terminal": {
"limits": [
{
"counter": "replace_zone_terminal_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}replace_zone_terminal 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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replace_zone_terminal. 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 replace_zone_terminal: 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.
replace_zone_terminal 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 replace_zone_terminal 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 replace_zone_terminal. 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.
replace_zone_terminal 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.